1.3 – Electoral systems
The election of Andy Burnham as the MP for Makerfield has created a vacancy for the position of Mayor of Greater Manchester. A by-election for the position has been scheduled for 30 July, although the mandate will only last until May 2028 (when Burnham’s own term was set to expire).
On 17 June, the Government made The Combined Authorities (Mayoral Elections) (Amendment) Order 2026, which brings into force the Government’s promise to reinstate the Supplementary Vote (SV) system for mayoral elections, as initially envisaged by the English Devolution and Community Empowerment Act 2026.
SV had been used for mayoral elections – and for the election of Police and Crime Commissioners – since the position of Mayor of London was created in 2000. However, the Elections Act 2022, passed by the previous Conservative government, replaced SV with the more traditional First-Past-The-Post (FPTP) system. The change was widely perceived to give the Conservatives the upper hand due to vote splitting on the left of British politics, thereby giving the Tories an advantage as only a plurality of votes were required, rather than an outright majority.
SV is a majoritarian voting system, requiring a candidate to obtain an overall majority (eg 50% + 1 of the vote) in order to win. This ensures that the winning candidate has more widespread support and can claim to have greater legitimacy for their actions once in office.
In SV elections, candidates are listed by name on a single ballot paper with two columns – one for first preference votes and one for second preference votes. Voters are required to vote twice on one ballot paper – once for their first-choice candidate with an ‘X’ in the first column, and once for their second-choice candidate with an ‘X’ in the second column.
Once polling closes, the total first preference votes for each candidate are counted. If any candidate has received a majority of the votes (e.g. more than half the total number of votes), they are deemed to be elected. If no single candidate has a majority, the two candidates with the most votes go through to the second round and all other candidates are eliminated.
The votes for the eliminated candidates are recounted. Any second preference votes for the two candidates still in the race are added to their total, and any second preferences for a candidate who has been eliminated are ignored. Once this process is complete, one of the two remaining candidates will have a majority of the vote and will be deemed the winner.
When this system was last used in the London mayoral contest in 2021, Sadiq was ahead on first preferences after the first round of voting with exactly 40% of the vote. Under FPTP, his plurality would have been enough to see him elected. However, under SV, a second round of counting was required, after which he was deemed elected with 55.2% of the vote. Andy Burnham won an outright majority in both the 2017 and 2021 elections fought under SV, which meant no second round of voting was required.
SV has a number of advantages. As well as conferring more legitimacy on the winner, it allows voters to give their support to their preferred candidate, even if they have little realistic chance of winning. Providing a voter’s second-choice candidate is one of the final two in the contest, their vote will not be wasted. In a crowded field – as we are increasingly seeing in the UK with the rise of Reform UK and the Greens – it prevents a candidate without widespread support from winning by virtue of simply having a small plurality. This also helps to ensure that extremist parties are less likely to win.
However, SV also has a number of disadvantages – it is still very difficult for smaller parties to succeed, as the winning candidate ultimately needs to be in the ‘top two’ after the first round of voting. Smaller parties ideally need a proportional voting system, such as STV or Closed List PR, in order to be able to gain representation. However, this does not work when only one person is being elected. SV also limits voters to supporting two candidates. Therefore, the Additional Vote (AV) may be deemed preferable, as voters can rank all the candidates in order of preference.
Without Andy Burnham on the ballot paper, it is possible that it will take two rounds of voting in Manchester next month. It will be interesting also to see how parties appeal for first and second preferences from voters who would not normally support their party.