Dyadic representation and Brexit: The limited effects of congruence in the 2017 UK general election

NICEP collaborate with the Research Centre for the Study of Parties and Democracy (Represent) to present Dyadic Representation and Brexit: The limited effects of congruence in the 2017 UK general election with Professor Chris Hanretty (Royal Holloway).

Abstract

Dyadic representation exists to the extent that legislators' actions are in some sense congruent with the preferences of their constituents. Dyadic representation can be secured by multiple mechanisms. One mechanism is the electoral sanctioning of incumbents who are "out-of-step" with constituency preferences. Investigating electoral sanctioning is difficult where there is limited within-party variation in legislators' positions. Any sanction received by out-of-step incumbents may be a result of the much more visible positions adopted by their parties.

We therefore investigate electoral sanctioning in an issue which divided parties. Specifically, we investigate the relationship between (a) the positions taken by members of the House of Commons prior to the UK's referendum on its membership of the European Union and (b) the vote-shares of those incumbents in the subsequent 2017 general election.

We argue that this represents a "most favourable case" for electoral sanctioning in Westminster-style systems: the vote was on a secondary dimension of British political competition (rather than a primary dimension which would have structured party competition), was highly salient, and led MPs to adopt stances that put them at odds with other members of the same party.

We analyse both aggregate and individual level data. Our individual-level analysis shows that respondents were 1.35 percentage points more likely to vote for incumbents who shared their position on membership of the European Union. This implies smaller aggregate gains: had all incumbents adopted the position eventually adopted by a majority of their constituents, those incumbents would have gained 0.27 percentage points.

We additionally test whether this relationship was entirely mediated through respondents' perceptions of MPs' positions, or was instead driven by increased campaign funding available to Leave (Remain-) supporting MPs in Leave- (Remain-) voting areas.