Labour should introduce the alternative vote system for mayoral elections

Labour’s English devolution bill is completing its passage through parliament. As currently drafted it changes the system for electing regional mayors, as well as local authority mayors and police and crime commissioners, from first past the post (FPTP, used in the 2024 and 2025 mayoral elections) back to the supplementary vote (SV) introduced for the London mayoralty in 1999 and used until the enactment of the Elections Act 2022. SV is better than FPTP; AV would be better still.

Supplementary vote is better than first past the post

It was a backwards step, taken by the Johnson administration, to have mayors elected under FPTP. One of the big advantages of mayors is their ability to act as convenors and champions for their whole strategic geography, setting a long-term vision for growth and working with councils of different political persuasions to deliver it.

Under SV, mayoral candidates had to appeal beyond their narrow party bases for the second preferences of supporters of other candidates. Having to secure a wider base of public support can bolster the authority of mayors to lead in a combined authority model in which they are first among equals rather than holding unilateral executive powers. That stronger mandate can empower them more effectively to advocate for their regions in negotiations with government and investors. 

First past the post, by contrast, opens the door to the election of mayors with a weaker electoral mandate – particularly at a time of growing fragmentation of the party system. In May 2025, for instance, four new mayors  were elected with a vote share ranging from just 25% (in the West of England) to 42% (in Lincolnshire). 

Labour’s decision to switch back to SV for mayoral elections from 2027 is therefore sensible, and in line with Institute for Government recommendations from May 2024. However, there is in fact a good case now to go one step further and move to the alternative vote (AV), under which voters can rank all candidates, rather than just selecting their top two.

Multi-party politics makes the alternative vote the best choice 

One reason to prefer AV is that it avoids the problem under SV of voters ‘wasting’ their second preferences by casting these for candidates who do not make the final round, either due to ignorance of how the system operates or just because of the unpredictability of electoral outcomes in a multi-party system. Research has shown that in SV elections with more than four candidates, the share of second preference votes that are discounted in this way rises to over half. ⁴ https://makevotesmatter.org.uk/news/2021/11/24/new-research-debunks-myths-about-the-supplementary-vote-system/   

In 1999, and even by the late 2010s when the mayoral model was established in places such as Greater Manchester and the West Midlands, it was possible to work out most of the time that the final decision would come down to the candidate of either Labour or the Conservatives. 

That is emphatically no longer the case. Polls show that parties in England are bunching in a way never seen before, with five potentially competitive parties. That makes the potential winner of an SV mayoral election something of a lottery – with the victory going to the candidate whose second preference voters are the best guessers and risking a lot of second preferences sitting on the discard pile. This could lead to mayors elected without a clear mandate, undermining their authority and the credibility of the system more widely. 

The way to avoid this is to use the system that Labour and most other political parties use to elect their own leaders – the alternative vote. Under AV, once a voter’s first choice is eliminated, their vote transfers to their next candidate still in the contest, until someone gets over half the votes. 

AV should have been the system from the start – but political fragmentation now makes it essential 

Labour (or a helpful peer in the Lords) still has time to amend the bill and put local democracy on a more secure footing.  Both Labour and the Conservatives have invested in making the mayoral model work – they now need to make sure that the electoral system produces mayors who can do the job.