This month’s elections for mayors and police and crime commissioners were contested under a revised voting system. In the first of a two-part blogpost, Alan Renwick examines how the shift affected the results. He finds that the impact was substantial, and that it specifically benefited the Conservatives. 

The elections held earlier this month for mayors and police and crime commissioners (PCCs) took place under a revised voting system. The Elections Act 2022 abolished the previous Supplementary Vote (SV) system, under which voters could express first and second preferences, in favour of straightforward First Past the Post (FPTP). The changed rules were applied in four local mayoral elections last year. But this year’s local elections offered the new system its first large-scale outing: every part of England and Wales had either mayoral or PCC elections; a few had both. 

So how did the new system fare? Did it affect the results? If so, whom did it benefit? This post endeavours to answer these questions, while a second part, which will be published tomorrow, will examine how the change affected the democratic quality of the elections in the round. 

How the change affected the results 

Ten combined authority mayoral elections and 37 PCC elections took place on 2 May. Under the new FPTP rules, Labour won nine of the mayoral contests, while the Conservatives won one. In the PCC contests, the Conservatives won 19, Labour 17, and Plaid Cymru one.  

We cannot be sure what the results would have been had the former SV system still been in place, but we can make estimates grounded in evidence. To do so, it is easiest to break the contests down into three groups.