The membership of parties abroad: a case study of the UK

Against a long trend decline in the membership of political parties in Western democracies, there has been an unexpected surge in the UK since 2015. Interestingly, this phenomenon has also been observed amongst British expatriates, despite their historically very low levels of engagement. Our paper explores this development using a multi-methods approach to investigate its impact across the three main parties, comparing the relative importance of supply-side and demand-side factors in each case. We show that the creation and development of British parties abroad are the result of two contrasting dynamics: a top-down one, which gives legitimacy and structure and in some cases, resources, and a bottom-up one, which gives purpose but also networks. Our survey of British expatriate party members reveals a diversity of triggers and motivations for membership, making an original contribution to the wider literature on party membership and on the political engagement of emigrants.


Introduction
Despite a growing body of academic research into parties abroad (Burgess, 2018; van Haute, 2020;Østergaard-Nielsen & Ciornei, 2019;Paarlberg, 2019) to which this special issue contributes, little attention has so far been given to their memberships. This is also true of the very extensive literature on membership of political parties, which constitutes one of the key subfields of party politics Scarrow, 1996Scarrow, , 2014; van Haute & Gauja, 2015;Whiteley & Seyd, 1996): rarely does research on political parties extend its scope to include membership of parties' organisational structures abroad. So while recent research shows that membership of political parties abroad is growing, we still know very little about why this is so or what membership entails for non-resident activists. What are the incentives for home parties to create membership structures abroad and what can members contribute to party activities, such as campaigning and fundraising, when they are inhibited by geographical distance? What are the motivations of emigrants in joining a party in their home country and what does overseas membership involve? Our paper seeks answers to these broad research questions through a case study of UK parties abroad in which we investigate the motivations of both parties and members, by means of textual analysis of party documentation and websites, of semi-structured interviews with party members and officials and of an on-line survey of members.
Our study adapts Scarrow's now classic distinction between supply-side and demandside perspectives, widely adopted by scholars of party politics to explain party membership and activism, to the analysis of UK parties abroad (Scarrow, 1996). Demand-side explanations involve calculations by party elites regarding the net utility of engaging party members. They have drawn on the literature on party organisations to analyse the importance of their recruitment strategies and changing models of organisation as well as cost-benefit analyses of party resources to evaluate the roles of the parties themselves in influencing membership levels. The many roles that party members play have been neatly summarised by Granik (2005: p. 599) as 'part supporter, part funder and part worker'. On the supply-side, the focus has been on the perspective of party supporters and their calculations about whether it makes sense to join a political party (Scarrow, 2014). The 'general incentives model' (GIM) developed by Seyd and Whiteley (1992), and grounded in the work of Clark and Wilson (1961), remains the gold standard here, as will be discussed more fully later.
As Kernalegenn and van Haute explain in the introduction to this special issue, incentives for political parties to create organisations abroad are tempered by certain constraints including low turnout amongst emigrants (Lafleur & Chelius, 2011), so from a demand-side perspective, a cost-benefit analysis is essential. However, parties abroad are not necessarily the result of top-down strategies by home parties; they can also be triggered by emigrant activists who can play an important role that has hitherto been under-researched ( van Haute & Kernalegenn, 2020). Supply-side factors are therefore also crucial, especially since the costs of political engagement can seem high in relation to the benefits gained (Waldinger, 2013). Studies of transnational electoral participation also offer some insights into the broader context of expatriate political engagement which can be motivated by expressions of belonging and symbolic attachment to the nation (Boccagni, 2011;Itzigsohn, 2012), or by the pursuit of specific interests (Bauböck, 2009), especially when the electoral system provides reserved seats for overseas representation (Collyer, 2014;Østergaard-Nielsen & Camatarri, 2020;Palop-García, 2018). But these wider forms of expatriate political engagement have not yet been closely analysed in conjunction with membership of parties abroad, as proposed in this paper.
In what follows, we first explain the choice of the UK as a case study and then set out our methodology in a second section. In the third and fourth sections we present our findings using the distinction between demand and supply side perspectives to explain party membership and in a final section we present our conclusions.
Case selection: why the UK?
In seeking to understand the drivers of membership of parties abroad, the UK presents an interesting paradox: despite historically high levels of emigration, it is 'an emigration nation without an emigrant policy' (Hampshire, 2013) and traditionally very low levels of expatriate engagement of any kind with the home country. Yet this has not prevented the development of British parties abroad, especially in recent years.
Estimates of the number of emigrants vary from 4.3 m (UN, 2019) to 5.6 m (Finch et al., 2010), representing between 6.5% and 8.5% of the British population. The UK always appears in the top ten countries of emigration in the world (UN, 2019). State engagement with the British diaspora is however, by international standards, underdeveloped (Finch et al., 2010). But nor have Britons abroad, traditionally 'out of sight, out of mind,' attempted to engage much with their home country, either through emigrant associations or politically, in contrast for example with citizens of France (Collard, 2013;Kernalegenn & Pellen, 2020) or Italy (Tintori, 2011;. Following their enfranchisement in the 1980s, few took up their new voting rights, as seen in Fig. 1, below. However, since 2015, there has been a sudden and significant rise in electoral registration, accompanied by the emergence of new forms of 'emigrant politics' amongst Britons overseas and a surge in membership of parties abroad. This was initially triggered by the introduction of on-line electoral registration in 2014, after which overseas registration trebled to 105,845 for the 2015 election (Fig. 1). The EU Referendum of 2016 then prompted another spike in voter registration, and the outcome of the vote sparked a tidal wave of angry comment on social media from Britons living abroad, but especially in the EU, that rapidly led to the creation of nationally-based campaign groups defending their EU citizenship rights (Collard, 2019). The election of 2017 saw a further increase in the number of overseas registrations as Britons abroad became increasingly aware of the potential impact of domestic politics on their lives, but in 2019 numbers surprisingly fell. Election reports from the Electoral Commission (EC) and the Association of Electoral Administrators (AEA) show that this was the result of the election being called at very short notice, meaning that many overseas electors were unable to complete the administrative requirements in time for their votes to be counted.
Within this wider context of a new sense of emigrant political engagement, there was also an unprecedented surge in membership of parties abroad after 2015, especially benefitting Labour and the Liberal Democrats. As explained more fully below, the two main UK parties, Labour and Conservative, had extended their memberships abroad following the enfranchisement of 'overseas electors' in the 1980ssimilar to what happened in other countries such as France (Kernalegenn & Pellen, 2020) or the USA (Klekowski von Koppenfels, 2020)but numbers were low and their activities had remained fairly low key. The post 2015 surge mirrored a similar trend in the home parties which also experienced a significant upturn in membership after a long period of decline. This phenomenon has recently been the subject of a comprehensive study Whiteley et al., 2019) on which we now draw to provide some explanatory context to the recent development of UK parties abroad.
Commenting on the long-term decline in party membership, which has, notwithstanding some nuances (Kölln, 2016;van Haute et al., 2018), been widely documented across all Western democracies since the 1950s (Katz et al., 1992;Van Biezen et al., 2012;Webb et al., 2002), Bale et al. refute the suggestion that it was caused by parties' loss of interest in recruiting. On the contrary, they claim that parties still see their members as valuable assets, providing 'a vital source of free labour' for campaigning and fundraising, and offering useful insights and connections into their locality (Bale et al., 2019: pp. 166-172). All parties have adopted a range of incentives to boost recruitment, including the introduction of 'supporter' status for those reluctant to commit to full membership. They explain the decline in UK party membership as lying primarily with supply-side factors: 'party membership declined because fewer citizens were prepared to make the commitment to join and remain involved in party life rather than because the parties gave up trying to recruit them' (Bale et al., 2019: p. 87). They cite the declining value of non-political selective benefits bestowed by party membership (such as leisure and cultural activities), and the erosion of expressive incentives in the form of social group identities linked to partisan affinities as the main factors.
Against this generalised long-term decline, they offer party-specific explanations for the recent strong surge in membership of the three main UK-wide parties. Of these, the most spectacular surge was that of the Labour Party following the 2015 election defeat and subsequent leadership contest. Among important explanations were ideology, notably for those who returned under Corbyn to the party that they had left under the neo-liberal turn of the Blair years, dissatisfaction with 'politics as usual' and the sense that Corbyn's style and commitment to internal party democracy would allow the voices of ordinary members to be heard (Audickas et al., 2019;Whiteley et al., 2019). The Liberal Democrats also benefitted from a membership surge but for different reasons. Bale et al. (2019) explain it partly as 'the losers' bonus', a rush to join the party after a dramatic election defeat in 2015 (p. 91), but also due to their open opposition to Brexit which attracted ardent Remainers, especially after the referendum. For the Conservatives, the position was more complex: obtaining reliable membership figures is notoriously problematic (Audickas et al., 2019: p. 9;Curtice, 2019), but the party seems to have experienced a decline from 2006 and a rise in 2018-19. The fluctuating figures were heavily conditioned by the changing politics of Brexit: while the prospect of a leadership election incentivised many to join, others left in protest at the government's handling of Brexit on both sides of the Leave / Remain divide, often switching allegiance to either the Brexit Party or the LibDems.
This short summary suggests that the recent political triggers for joining parties in the UK after 2015 were a combination of electoral dynamics, party leadership elections and Brexit. Can the same trends and similar reasons be identified for membership of the parties abroad? We know that emigrant citizens tend to hold specific socio-political interests (Østergaard-Nielsen & Ciornei, 2019;Paarlberg, 2019) and experience the consequences of homeland politics in a specific way (Kernalegenn & van Haute, 2020). As the French case demonstrates, they are very sensitive to institutional changes that concern them but also to homeland political dynamics when the image of their home country and potentially their own interests are at stake (Kernalegenn & Pellen, 2020). We can hypothesise that whereas British abroad might be influenced by electoral dynamics and party leadership elections in the UK, but in a more dulled way, Brexit should have even more influence, at least among the British living in Europe, since it has very concrete consequences for many of them. Although the figures are notoriously unreliable, Table 1 gives a snapshot of the state of play of membership of the three main UK-wide parties in 2019.
In investigating the trends in membership of UK parties abroad, we pose two main sets of research questions. On the demand-side, what were the drivers behind the initial creation and subsequent development of UK parties abroad? If, as Bale et al. (2019: p. 166) argue, UK parties value members as 'footsoldiers' on the campaign ground, providing helpful links in the constituency, what purpose could non-resident members serve? What role did the party leaderships play in boosting the membership surge after 2015? On the supply-side, what are the motivations of expatriates who join UK parties abroad and how do they compare to those of UK residents? The literature often suggests that launching an extraterritorial branch is primarily a bottom-up initiative, even though the process of institutionalization by the mother party is afterwards usually rather quick (Jakobson et al., 2020;Kernalegenn & Pellen, 2020;Klekowski von Koppenfels, 2020). What are the dynamics of parties abroad in a British context? In the following section we set out the methodology adopted to answer these questions.

Methodology
The scope of our study is limited to what are now considered to be the three UK-wide main parties, as in the analysis by Bale et al. (2019). The other parties, UKIP, the Brexit Party, the DUP, SNP, Plaid Cymru and the Green Party, have not yet developed any formal institutional organisations for non-resident members (though the SNP has a branch in Brussels). This is partly due to the marginal importance attributed to overseas voters in UK politics and is partly the logical consequence of applying a costbenefit analysis to an unquantifiable level of support. But for the last three of these parties, an ideological approach to 'inclusive' citizenship grounded in residence rather than nationality (including long-term non-citizen residents) no doubt also plays a role. Thus, our analysis will focus only on the Conservatives, Labour and the Liberal Democrats. Given the lack of official data, that makes British expatriates a 'hard to reach' group, we adopted a largely qualitative approach to both supply and demand-side questions, based partly on textual analysis of party documentation and websites and partly on 33 semi-structured interviews with party members and officials between July 2015 and August 2019. This period matches that of the research project conducted by Bale et al. (2019). Interviewees were contacted initially through the parties' websites and Facebook pages, and further contacts were made through snowballing and desk research. Most of the interviews took place in Western Europe (France, Belgium, Germany, Spain and Switzerland), the USA and Hong Kong.
In order to objectify and test our findings, our qualitative research was complemented by an online survey, using LimeSurvey, adapted from the MAPP comparative membership survey, 1 sent to British party members abroad in June 2019. Since we were unable to obtain access to opinion polls or lists of members, we used the snowballing technique to roll out the survey to party officials and members identified through websites and social media, and various networks were targeted through Facebook and twitter. Therefore, the survey is not based on a representative sample, which limits our ability to generalization, but our findings nevertheless deliver original insights into this otherwise inaccessible target population, especially since it builds upon in-depth and extended qualitative fieldwork. We obtained 167 responses for the three parties: 31 from Conservatives, 68 from Labour, 68 from Liberal Democrats. Therefore, based on Table 1 above, 5.7% of the members of CA, 2.5% of LI members and 3.4% of LDA members answered the survey.
The results of our analysis are presented in the following two sections, addressing first the demand-side and then the supply-side questions.

The development of British parties abroad and their role in recruiting expatriate members
This section focuses on the demand-side dimension of the emergence and development of the membership of British parties abroad. It first provides a brief explanation of the historical context which triggered initial interest in overseas recruitment before tracing the origins and development of British parties abroad. We conclude by examining the recent surge in membership abroad and its impact on the existing organisational structures.

Expatriate enfranchisement as the initial trigger
The emergence of UK parties abroad followed from the introduction of voting rights for expatriates by the Representation of the People Act of 1985, confirming that enfranchisement of emigrants is an opportunity structure for the creation of parties abroad ( van Haute & Kernalegenn, 2020). Pressure to extend the franchise to nonresidents had come mainly from Britons working in EEC institutions, but the idea was highly controversial for two reasons. First, because it represented a major departure from the traditional principle of voting rights being tied to residence. Second, because in the 1980s those living 'overseas' were widely thought to be disproportionately affluent and therefore more likely to vote Conservative. The strength of Labour opposition to the idea of expatriate enfranchisement meant that, initially, votes from abroad were only allowed for the first five years after leaving the UK, but this time limit was increased by the Conservatives to 20 years in 1989 before being reduced to 15 in 2000 when Labour came into power. Although there has been a significant diversification of the expatriate population since then, the attitudes of the two main parties towards the issue of overseas voting have not moved with the times, as demonstrated during parliamentary debates on the recent Overseas Electors Bill 2017-19 (Collard, 2019). These embedded attitudes coloured their contrasting approaches towards the creation of an overseas arm of the party, seen essentially as a vehicle to get supporters abroad to register to vote for them.

The origins of British parties abroad
Conservatives Abroad (CA) Unsurprisingly, the Conservative Party, anticipating electoral gains from the new legislation allowing registration of expatriates, was the first to create a specific 'overseas' party structure in 1986, called Conservatives Abroad (CA). It took the form of a dedicated department inside the Conservative Party International Office under the leadership of David Smith. He later wrote that its main goal was to collect 'votes and notes' (i.e. political donations) (Tether, 1994: p. 81). He has described how he began from the 'anecdotal belief that there were quite a lot of expats living in Spain.
[…] A Constituency Agent at heart, I began the process of forming Conservatives Abroad branches.
[…] Recently retired agents and Central Office Agents (COAs) were sent to resorts in Spain and Portugal over the Winter, on minimal expenses tasked with finding Conservatives to form branches' (Smith, 2009). By July 1986, CA had established 28 local branches, tasked with informing like-minded people of their new voting rights and encouraging them to register. Central Office in London provided support with the cumbersome registration process, including finding proxies since postal voting was not then allowed.
The party's interest in recruiting abroad means that CA has always been run directly from within the International Office in London, but its structure remains loose and informal. Due to party centralisation (Bale et al., 2019: p. 173), membership is now administered by the Cities of London and Westminster Conservative Association (CLWC A). Overseas members share the same benefits as members of UK Associations: participation in the Conservative Policy Forum, attendance at party conferences and a vote in party leadership elections. Branches are expected to conduct fund-raising activities and to seek donations as well as encourage electoral registration, thus maintaining CA's original quest for 'votes and notes.' Despite CA's efforts, the number of registered overseas electors never rose much above 30,000 until very recently (see Fig. 1 above) and the party's interest in the overseas electorate seems to have dwindled after academic analysis of the 1992 election suggested that its overall impact on electoral outcomes did not really justify the investment of significant resources (Pattie et al., 1996;Tether, 1994).
Labour international (LI) By contrast, given its instinctively hostile attitude towards expatriate enfranchisement, Labour was slow to see the benefits of creating a party structure abroad and it was only in response to growing pressure from party members around the world that Labour International was formally created in 1997. Before that, the name had been used to denote a loose association of Labour Groups created by active members in about 20 countries, the oldest and most influential of which was in Brussels (Pyke et al., 2013). Archival evidence shows that from 1992 onwards, LI members campaigned to try and persuade the leadership and the Parliamentary Labour Party (PLP) to recognise their potential contribution by fund-raising and encouraging Labour supporting expatriates to register to vote. 2 Some branches also argued for official standing within the party and representation at the annual party conference, which was agreed in 1996 with HQ, leading to a new party constitution formally integrating LI.
LI was structured as a Constituency Labour Party (CLP) like other UK CLPs with the rulebook amended to include overseas membership in local branches. Its executive body, the Labour International Coordinating Committee (LICC), was elected every two years, meeting face to face annually at the party conference. But LI never established a close relationship with party leaders and it failed to prevent Labour's reduction of the time limit of the overseas franchise in 2000. Under Tony Blair's leadership, membership gradually declined, as in the home party, from about 1,000 to 500 worldwide. 3 Liberal Democrats Abroad (LDA) The third main UK-wide party, the Liberal Democrats, was formed from the merger in 1988 between the old Liberal Party and the break-away group from Labour, the Social Democratic Party (SDP). The party's position towards expatriate voting during the key parliamentary debates was ambivalent: although initially championing the enfranchisement of Britons working in EEC institutions, it also espoused a more idealistic vision of establishing reciprocity of voting rights between Member-States. This ambivalence, combined with its limited resources as a smaller party, meant that formalising a structure abroad was not a priority. Nevertheless, it had a small but active local party in Brussels, 'Brussels and European Liberal Democrats' (BELD), animated mainly by employees in the EC/EU institutions, and an informal entity called 'Rest of the World (ROW)'. Being an administrative anomaly, BELD was attached to the Federal International Relations Committee (FIRC) (a subcommittee of the Federal Executive) in London. After the formation of the coalition government with the Conservatives in 2010, the head of the International Office in London attempted to emulate the other two main parties by launching an organisation for LibDems outside the UK called 'Liberal Democrats Abroad' (LDA), with a view to attracting overseas votes that could be critical in marginal constituencies. 4 However, this top-down venture was short-lived as other matters were prioritised. This brief summary of the creation and development of UK parties abroad shows that attitudes to expatriate enfranchisement (and expectations of electoral gains or losses) were the key driver on the demand-side, but that the activism of party members abroad also played an important role: this became the dominant driver in the surge in membership of parties abroad after 2015, as presented in the following section.
The revival of membership of parties abroad after 2015 The developments we identified earlier that combined to trigger an unprecedented surge of political engagement amongst Britons abroad from 2015 onwards, affected the organisation and memberships of UK parties abroad in very different ways.
For CA, the experience began well since it had played an important role in orchestrating the increase in overseas electoral registration in 2015, reflecting the Conservative Party's renewed interest in the potential electoral gains to be won abroad. The unwelcome experience of coalition government with the LibDems following the 2010 election had caused the leadership to revive CA's activities in the hopes that expatriate Tory votes might swing outcomes in enough marginal constituencies to deliver a majority in the 2015 election. 5 In 2012, the Conservative Party International Office was reorganised under a new Chair, Geoffrey Clifton-Brown, who ran a personal campaign in Parliament to increase the potential gains from the overseas vote by abolishing the 15 year time limit in favour of 'Votes For Life' (VFL). Following the recommendations of a cross-party Working Party which he instigated, he was instrumental in orchestrating the Electoral Commission's awareness campaign amongst expatriates (an 'underregistered' part of the electorate), encouraging them to register. At the same time, the new Chair of CA, Heather Harper, oversaw a professionally organised campaign called 'Think of Three' to involve members in encouraging electoral registration and phone canvassing for candidates in targeted constituencies. 6 The inclusion of VFL in the party manifesto in 2015 could be seen as CA's reward for its contribution to the election victory since members had long been campaigning for this. However, CA then suffered from the political fallout of Brexit 7 and from the government's effective withdrawal in 2019 of its backing for a Conservative Private Member's Bill introducing 'Votes For Life' (Collard, 2019), which suggested the party had acknowledged that it could no longer assume support from the overseas electorate, at least not in the EU. Although a post 2019 election survey of Britons abroad shows that the Conservatives had lost the votes of most of its previous supporters, this did not have any impact on the final result, which gave the Tories a large parliamentary majority (Collard & Webb, 2020).
For LI, it was the election of Jeremy Corbyn as leader in 2015, followed by a second leadership contest in 2016, that triggered a major political and organisational impact. LI membership soared to around 3,500, making it one of the biggest CLPs in the party. According to Steve Hudson, provisional co-chair of Momentum International, 8 these were mainly 'rejoiners' previously alienated by Blair's leadership. More recently, membership fell again as in the UK, reflecting the party's ambiguous position on Brexit and 5 https://www.conservativesabroad.org/files/ca_directory_october_2015.pdf (last accessed 11th May 2020). 6 https://www.conservativesabroad.org/files/annual_conference_programme.pdf (last accessed 11th May 2020). 7 For example, a Conservative living in Spain explained in an open question to our survey: 'Our local Branch has all but disintegrated because of the strong feelings surrounding Brexit'. 8 Telephone interview, 9th May 2019.
ongoing internal arguments. But in 2020, LI still claimed over 2,700 members, spread across 23 branches worldwide. 9 The LICC renewal in the Spring of 2017 led to a landslide victory by members of Labour International Left Alliance (LILA), a left-wing grouping with the collective aim of turning LI into an active campaigning organisation. They introduced a new constitution from April 2019 bringing LI more into line with CLPs in the UK, replacing the Coordinating Committee (LICC) with an Executive Committee (LIEC). The LILA team claims to have increased the number of functioning branches from 3 to 20 and transformed the democratic nature of LI by skillful harnessing of new technologies. 10 The changes were however not well received by some of the original LI members whose candidates' statements from 2019 revealed deep acrimony and internal divisions, as in the home party, especially over the party's ambiguous position over Brexit and its hostility towards VFL. These divisions were amplified by the devastating election defeat of 2019.
For the Liberal Democrats, it was the EU Referendum that triggered a second attempt to institutionalize Liberal Democrats abroad, this time from the bottom up, following a significant and spontaneous surge of new membership applications abroad following the 2016 EU Referendum. 11 This led to the creation of three new 'local' 12 parties abroad under the umbrella of Liberal Democrats Abroad (LDA). The quadrupling of BELD's membership to about 1500 prompted the creation of its first separate branch in France comprising about 500 members. 'LibDems in France' soon chose to split from BELD and form a separate local party from April 2018, when BELD was relaunched as 'LibDems in Europe'. A third local party was then set up from the remnants of 'Rest of the World' called 'LibDems Overseas'. Reflecting the home party's federal structure, there are now therefore three separate local parties grouped under the revived label 'Liberal Democrats Abroad' (LDA), each with its own slightly different constitution.
Administratively, LDA remains a sub-committee of FIRC, which manages the relationship between the home party and the three local parties abroad. This new structure was formally launched in September 2018.
LDA clearly owes its very existence to the political fallout from Brexit, but the leadership election in July 2019 also inspired new joiners. In keeping with the party's strong democratic ethos, all members can vote in party leadership elections and attend Annual Conference as well as contribute to policy proposals within their own branch or local party. Since LDA is a new venture for the LibDems, its activists were highly motivated to demonstrate their value to the main party by playing an active role in election campaigning and fund raising for selected candidates. But the resounding defeat in the 2019 election also led to recriminations within the party over its failure to make electoral gains from the massive support it won from Britons in the EU (Collard & Webb, 2020).

Concluding remarks on demand-side factors
This brief account of how the three main UK parties abroad came into existence and developed their memberships over time shows how they have been driven both by top-down concerns with expected electoral gains, and by bottom-up pressures from active party members and supporters for recognition and organisational status within the main parties. The Conservative Party was the pioneer in seeking a presence abroad, while Labour and the LibDems have been merely reactive. Therefore, whereas demandside factors best explain the creation of CA, it was supply-side drivers that are most appropriate for LI and LDA.
Following the decisive Conservative victory in the December 2019 election, the opposition parties have been thrown into a state of flux, and the future for their organisations abroad looks bleak: despite a massive backlash against the Tories amongst Britons in the EU (Collard & Webb, 2020), neither Labour nor LibDems were able to harness this to their overall advantage. Yet parties don't exist only to win elections, they also fulfil the needs of the members who join them. The following section examines the motivations of members of UK parties abroad, based on results of an online survey and semi-structured interviews.

The motivations of party membership among expatriates
When analysing party membership from the supply-side perspective, the 'general incentives model' (GIM) developed by Seyd and Whiteley (1992) remains the standard reference point. Focusing on why people join parties despite the costs involved (the paradox of party affiliation), they outlined a number of motivations: attachment to a party's principles or a belief in its leadership (expressive incentives); support for the party's policies or opposition to the policies of a rival party (collective incentives); support for the democratic process or promotion of the interests of the nation (altruistic incentives); influence of family or friends (social incentives); desire to mix with likeminded people or learn about politics (process selective incentives); and enhancement of career opportunities (outcome selective incentives). Likewise, Scarrow (2014) later categorised three distinct benefits that parties provide for members: social and psychological (the provision of group identity, leisure activities, status), material (policy benefits, consumer discounts, education, training, patronage and general careerism) and political (to advance a cause or oust current government, to influence party decisions).
Empirical research shows that party members are essentially motivated by political incentives and, to a lesser extent, socio-psychological incentives. Material incentives are much less important or, at least, survey respondents are reluctant to acknowledge them ( van Haute & Gauja, 2015). Bennie (2015) and Bale et al. (2019) confirm these findings for the UK. In all surveys since the 1990s, ideological incentives motivate between 61.4 and 90.2% of party members, whereas material incentives are mentioned by only 2% of respondents at most (Bennie, 2015: p. 176). Bale et al. (2019) confirm the prioritisation of political incentives across all main parties, 13 but they add that a trigger is also needed to activate the decision to join a party (2019: p. 89; Dommett & Power, 2018).
There is little information so far in the literature concerning the membership of parties abroad, though recent publications have mentioned the importance of socialising for Estonian (Jakobson et al., 2020) or American (Klekowski von Koppenfels, 2020) party members abroad, with the participation in celebratory events (Estonian Independence Day, Fourth of July barbecues…). Klekowski von Koppenfels (2020;pp. 50-52) also show that identity and partisanship are important motors for Democrats Abroad, notably during the Iraq war or after Donald Trump's election, when the party abroad became a tool to participate in anti-Iraq War and anti-Trump activities, and to show that not all Americans supported the president and his decisions. In Romanian parties abroad, on the other hand, socializing is limited. Emigrants tend to join because of personal links with party members (Gherghina & Soare, 2020).
To develop a more systematic knowledge, our research findings drawn from the online survey and interviews are discussed under three headings: triggers, political motives and socio-psychological and material motives.
When does an expatriate join a political party abroad? The triggers of commitment Three main triggers were identified earlier to explain the recent surge in party membership in the UK: electoral dynamics, party leadership elections and Brexit. Our interviews and survey confirm that similar reasons apply to expatriates, albeit with different weights. Whereas 46.2% of respondents to the survey were already member of their party in 2015, 53.8% became members in 2015 or after. The 'losers' bonus' is illustrated by P.D., Hong Kong resident who joined LDA in 2015: 'In 2015 we suffered very very badly in the general elections and I thought that it was time for me not only to vote but to act... support the party' (P.D., Hong Kong, 13/02/2019). The election defeat of 2015 and Labour leadership election of Jeremy Corbyn was also a crucial trigger to join Labour International: 'with the Corbyn people, we've got a whole new inrush of newly interested people' (I.W., New York, 09/11/2018). Our survey results ( Beyond personal convictions, joining a party was also motivated by the will to bring expertise, especially on the issue of Europe for Brussels based expatriates. But for K.M., a CA member in Hong Kong, Brexit was also 'most certainly the catalyst' for opposite reasons. Comparing Brexit to the election of Margaret Thatcher in 1979, he saw Brexit as a catalyst for pride in Britishness. Expatriate since 1994, he couldn't vote, but found that Brexit 'reenergized' him, 'rebrought [him] into UK politics', motivating him to reestablish his 'conservative roots' (K.M., Hong Kong, 12/02/2019). Brexit also triggered 14 That was massively condemned by respondents to the survey, with the exception of Conservatives: whereas 56% of Conservative respondents thought it was a good thing, no Lib-Dems or SNP and only 5% of Labour respondents shared that opinion. However, the survey was done in 2019, so the most anti-Brexit Conservatives might have already left the party. joining a party out of a desire to be part of the ongoing debate, as for D.A., a CA member in New York: 'I was just kind of desperate to talk to people about […] what was going on; likeminded, people with different opinions… just to have a debate. And I didn't really know […] what I thought about the discussion. […] I can see points on both sides of it. And I just wanted to have a debate, and there was no forum to do that.' (D.A., New York, 27/09/2018) Finally, Brexit triggered joining a party because of more practical concerns about the future: 'One thing that's not clear to me right now is whether my existence here […] is based on a sort of an EU agreement, or whether there is a bilateral Swiss-British agreement.
[…] Our status is because Britain's EU membership […] So I think we need to make sure that our voice is heard as part of Brexit as well.' (T.M., LDA, Zurich, 04/07/2017) Alongside electoral dynamics and party leadership elections, Brexit was therefore a crucial trigger for the strong development of membership of British political parties abroad after 2015, not only for its strong emotional dimension but also because it changed the rules for Britons living abroad, often without their consent.

Political reasons for joining a political party abroad
Political (and ideological) incentives are by far the main reason given by members for joining their party, and members of UK parties abroad are no exception. Most political reasons suggested in the survey are very important to a majority of respondents, and if we add those who answered 'somewhat important', all are important to a majority of respondents of each of the three parties, but with important contrasts between them. Patriotism, assessed by the will to show one's continued commitment for the UK and to promote the interests of the UK, is 'very important' to CA members: 100% answered either 'very' or 'somewhat' important, compared to 58.3% for LI members and 69.7% To oppose other political parties 31.8 60.0 57.9 The result denotes those who said that this reason was very important for LDA members. 15 By contrast, LI and LDA members overwhelmingly ranked their attachment to the party's principles as a 'very important' reason for joining, compared to CA members for whom it was less important. Collective policy incentives are slightly less important, but with a strong contrast between CA members, who emphasised influencing party policy on a particular issue, and those of LI and LDA, of whom almost 90% say they joined to oppose other political parties. Although political reasons given by our respondents resemble those found in Bale et al.'s (2019) survey, there are subtle differences shown by our qualitative data. To explain them we focus first on altruistic patriotism then on party policy.
Altruistic patriotism or fighting for the country they would want to go back to When discussing their links to the UK, expatriates frequently explain that they joined a British political party abroad to fight for the country they would want to return to, where their kin can live decently 'When you've been away a while, and they take your vote away after 15 years, […] you're inclined to think more 'Why bother?'. But… I think it is important, because I thinkok, I can't vote, but it is a responsibility as a citizen, a responsibility to make sure that your country is in good shape (laugh). And that […] the political system works, democracy works.[…] We'll see what comes out of this mess… […] I think, for the moment though, our country needs us (laugh) more than Belgium.' (D.G., Brussels, 12/07/2018) Patriotism is therefore both emotional and rational.
Contribution to party policy Membership of parties abroad is also often about policy and ideology. Two specific elements appear regularly: first, the defence of the specific interests and needs of expatriates, second, the desire to share their knowledge as expatriates, notably about their host country. Indeed, 'if you're expat you're going to have slightly different concerns than someone who is living back in the UK' (S.G., Washington, CA, 18/09/2018). In Hong Kong, for example, Conservatives have a 'Conservative policy forum group', which meets every 2 months, and 'contributes ideas back to the party in the UK' (K.M., Hong Kong, 12/02/2019).
The demands of the different parties are quite similar, as far as their status as expatriates is concerned: 'Some of the issues we want to address as expatriates are the whole question of voting, pensions, compatibility, systems like that, because a British pensioner who goes to Australia doesn't get any increase in the pension from the minute they land in Australia. Because there's no reciprocal treaty. ' (I.W., New York, LI, 09/11/2018) Activists abroad want to make sure their concerns are acknowledged and represented. Among their priorities, as summarized in a policy paper prepared by LibDemsOverseas, 16 are 'Votes for Life' (i.e. 'removal of the 15 year time limit'), 'full UK pension' (i.e. 'receive inflation-related increments'), 'improved Foreign Office support' and 'equivalent access to UK Universities' (i.e. 'give British nationals overseas the same rights as UK residents when applying to UK Universities and paying their fees').
On the other hand, as pointed out by K.M., they also contribute to the UK, by sending ideas and knowledge about what's going on abroad: 'We do have a […] very local contribution.
[…] As Brexit unfolds, that's gonna become more and more important. London, the UK needs to re-engage with the rest of the world […]. They want people abroad to get that overseas perspective and feedback information, how things are done, what's going on, how can we shake things so we can actually contribute back the UK. ' (K.M., Hong Kong, CA, 12/02/ 2019) In other words, party members abroad are sending political and ideological remittances back to their home party (Krawatzek & Müller-Funk, 2020).

Socio-psychological and material reasons to join a political party abroad
As discussed earlier, research tells us that material reasons are almost anecdotal for joining parties, whereas socio-psychological ones are secondary (Scarrow, 2014: p. 158). The results of our survey (see Table 3 below) confirm that careerist motives are minor (but not inexistant), whereas social norms incentives (i.e. influence of family or friends) are quasi inexistant among the surveyed expatriates. Socializing (selective process incentives), however, is relatively important for CA members but much less so for those in LI. The contrast is particularly striking when the national dimension is included: 59.1% of CA members say that meeting fellow Britons is an important reason for joining the party, compared to only 18.3% for LI and 8.9% for LDA. However, meeting politically like-minded people is important for all party members, though less so for LDA: 56.2% compared to 77.3% for CA members, and 83.1% for LI. Our interviews reinforced the impression that socio-psychological reasons for joining are slightly more important for party members abroad than at home. Two important themes emerged: being in a political setup they could understand and participation in party meetings.
Being in a familiar political setup Many interviewees explained how they joined a political party abroad to be in a political setup they understand, with a familiar language and rules. As C.O. explained, 'in Australia, New-Zealand, the political setup is not different from the UK. You're more likely to concentrate on joining the local political parties' (C.O., Leuven, 09/07/2018). But the situation is different in most other countries. He therefore sees 'the international organization as somewhere where they can talk to like-minded people, in their own language. Rather than trying to do the difficult job of integrating into […] a community at the level of political campaigning. Which is quite a big step to take if it's a different language in a different culture.' This is notably the case in Belgium, as G.H. explains: 'My language skills are just not good enough […] to engage in any way in Belgian politics. And I don't have the affinity. Because the cross currents of Belgian politics are very different. It's not a straightforward Left-Right split.
[…] You have many more parties here… with different regional and religious affiliations. So, it's not something I would be able to understand, or engage in as far as I can say, without being a lot more immersed in Belgium society.' (G.H., Brussels, 21/08/2018) Completely fluent in neither French or Flemish, G.H. would feel quite alien in a Belgian party, all the more so because the country is not only defined by the left-right cleavage, but also by a linguistic cleavage. Similar arguments were given in Hong Kong, where fluent Cantonese is essential to fully participate and where the logics of commitment are radically different (K.M., Hong Kong, 12/02/2019). G.H. and K.M. want to be politically active, meet like-minded people, but the only place where they think they can do it meaningfully and at ease is CA.
Party meetings Party meetings can focus on networking, or on policy discussions. The kind of meetings that our interviewees mentioned most however, are meetings with a special guest, as in Brussels: 'Brussels Labour meets on a monthly basis.
[…] There'd be a discussion about a particular theme and, typically, if you have a guest speaker, […] have the opportunity to do questions on the sessions, and the meetings will typically be off the record Meetings are therefore not only about socializing, but also offer an opportunity to understand better the functioning of British and European politics, with insider information from high-ranking personalities. Party members also meet quite often around meals or drinks, formally or informally, but meeting high profile party members is particularly valued within CA and interviewees are very keen to list all the 'celebrities' they've hosted: 'We've had, throughout this year… Sajid Javid… who is now Home secretary.
We've had… David Mundell… Government minister, Secretary of state for Scotland. We've had… Lord Hague, for instance, as well… Geoffrey Clifton-Brown… There's been Liam Fox, typically as well… So, big high profiles.
[…] We've also had Conservative MPs, British MEPs visits. So again, it's meals and social events around that.
[…] All these names […] you hear about and you see on TV and, suddenly, they sit next to you. You suddenly become engaged with them on a one-to-one basis. It's quite something.
[…] When those ministers do come, you can actually have direct conversation, direct contact with people, with far more significant influence, and they're gonna take that back to the UK.' (K.M., Hong Kong, CA, 12/02/2019) Visits from high-profile members are a way of attracting people, of giving meaning to being a member of CA. This is also a way of creating strong in-group bonds, and making participants feel special, having direct access to the centre of British politics, a good way to stay connected with UK politics.

Concluding remarks on supply-side factors
According to our survey, whilst expatriates' motivations for joining a party were largely similar to those of UK residents, there were some noteworthy differences beyond the attempt to draw attention to specific concerns and interests of non-residents. Patriotism, and notably the continued commitment for the UK, was very important as a motivation, especially for CA members. The desire to transmit to the UK expertise gained in the country of residence was another recurring theme. Finally, socializing was also an important motivation: while meeting fellow Britons was especially important for Tories, most party members said they enjoyed being in a political setup they could understand and they appreciated opportunities to engage with others who shared their political views.

General conclusion
In this paper we have proposed an original analysis of membership of parties abroad based on a case study of the UK, using an online survey and semi-structured interviews with officials and members of the three main parties abroad. We have shown that in answer to our main research questions regarding both demand-and supply-side factors, overseas membership is closely linked to developments in domestic politics. However, we have also explained why there has been strong variation across the parties: whilst the Conservatives have been pro-active in organising abroad in anticipation of electoral gains, Labour and the LibDems have been more reactive, only formalising structures under pressure from activists abroad. Therefore, the branches of British parties abroad are the result of two dynamics: a top-down one, which gives legitimacy and structure and in some cases, resources, and a bottom-up one, which gives purpose but also networks.
Building on the recent research findings of Bale et al. (2019) we have also demonstrated that the recent surge in party membership abroad mirrored that of membership in the UK in many ways and for many of the same reasons, albeit Brexit is an even more important trigger amongst expatriates. However, we have also reported interesting differences in what motivates expatriates to join a party abroad and we have shown that it was mainly party activists not leaders who led this resurgence, notwithstanding certain party-based specificities.
The level of party membership abroad in 2019 at around 5236 for the three main parties, may not be high compared to the number of Britons living abroad, but this represented about 1.78% of the (roughly) 300,000 registered overseas voters. This is still lower than figures for the UK as a wholeparty membership of around 1 m (Audickas et al., 2019) representing 2.1% of the (estimated) 47 m registered electors -, but nevertheless it marks a notable break with historically low levels of engagement with parties abroad. We have shown that this was the result of the developments in UK politics discussed above. But this then begs the question as to whether or not this level of membership can be sustained in a post Brexit context: will the post 2015 resurgence of UK parties abroad prove to be shortlived? Recriminations within the parties defeated in the 2019 election will no doubt impact on individual responses to the value of party membership. But for those who have lost their voting rights in the UK due to the 15 year rule, party membership remains one of the only opportunities to express a political link with the home country and to have a voice there. Future research must seek to establish whether Britons abroad maintain their recent appetite for political engagement or whether they turn away from the country and the parties which many feel have let them down.
On a more theoretical level, by focusing on party members and membership and by combining a supply-side and a demand-side perspective, this paper makes an original contribution to the broader literature on parties and on transnational politics. We confirm that the development of emigrant party branches is closely linked to that of external citizenship and voting abroad. Despite the size and relative density of the diaspora however, the development of British parties abroad has been very slow, parallel to that of electoral registration. If triggers are important, and Brexit is an exceptionally important one, we have also confirmed the multifaceted reasons for joining a party abroad. Studying transnational politics from both a top-down and bottom-up perspective can be fruitful, and more research should be done on other ideal-typical cases or with a comparative approach to have a more complete understanding of migrant politics.