When we started Nudge Knowledge, we said it would allow us to indulge our collective inner Nudge Factory geekiness. With the upcoming Metro Mayor elections – which you should know all about if you’ve been reading our Nudge Knowledge series of briefings – we thought we’d take a dive into the numbers and have a detailed look at the Supplementary Vote system which will be used in all six of these elections.

(You can also download our more detailed briefing note on the Supplementary Vote here.)

What is the Supplementary Vote?

The Supplementary Vote (SV) is similar to the Alternative Vote (AV), on which the UK held a referendum in 2011, and is used in elections for a single position where there are more than two candidates. Unlike AV, where electors choose as many candidates as they like in order of preference, with SV the elector only chooses their first and second choice candidate.

When the votes are tallied, if one candidate gains more than 50% of first preference votes, they are elected straight away. If nobody receives more than 50% of the first preference votes, then the two candidates with the highest share of the vote go into a second round and the other candidates are eliminated. The second preference votes from the eliminated candidates are added to those of the remaining two candidates, and whoever has the largest number of votes from the two rounds combined is elected.

Why use SV?

Why not just use the good, old-fashioned, tried and tested, simple to understand, first-past-the-post (FPTP) system that is used for Westminster Parliamentary elections and for council elections across England and Wales, where there is only one round of voting, and the candidate with the single largest share of the vote wins?

The answer is that where a single person was being elected to be responsible for new, whole authority-wide devolved positions – for instance a directly elected Mayor or Police and Crime Commissioner – it was felt that the winning candidate needed to demonstrate a broader mandate than that gained through FPTP.

SV is seen by some as preferable to FPTP as it can encourage candidates to build a broader campaign, as winning second preference votes can be crucial to success. It is also often seen as preferable to AV in that it only has two rounds of voting, so is more simple. Critics may say, however, that unlike AV, it does not ensure that the winning candidate has the support of 50% or more of the electorate, and because second preferences will only count for the two candidates who get the biggest share in the first round, it gives an advantage to candidates from the bigger parties.

Where is SV used?

Regardless of those pros and cons, SV is currently used in the following elections across England and Wales:

  • Local authorities where residents have voted to introduce a directly elected Mayor;
  • Local authorities which have, since 2007, introduced a directly elected Mayor via a Council decision;
  • Police and Crime Commissioner elections;
  • Election of the Mayor of London;
  • And now, for the new Metro Mayors

How does SV work in practice?

The chart below demonstrates how SV works in an actual election. It shows how first and second preference votes were cast, and second preference votes reallocated, at the most recent London Mayoral election, in 2016.

After the first round, Sadiq Khan and Zac Goldmsith received many more votes than any of the other candidates, but neither reached 50% (Khan got 44.2% in the first round). The other candidates were therefore eliminated, and their second preference votes redistributed: the chart shows where these went (and note that if a second preference vote was for neither Khan nor Goldsmith, it is discarded). Zac Goldsmith received fewer second preference votes than Sadiq Khan (161,427 to 84,859) and so was unable to make up his first round deficit – and Khan was duly elected.

It is perhaps worth noting the high number of missing second preference votes (384,243 simply didn’t chose a second preference) and where voters put the same candidate for their second preference as for their first (220,311). Whilst this may have been a conscious choice to only support one candidate, it may also demonstrate that voters have not entirely got to grips with the SV system. The fact that a further 32,217 votes were declared invalid due to voting for too many candidates in the first choice column perhaps backs this assessment up.

A Short History of SV in England and Wales

The Supplementary Voting system has been used in England and Wales since 2000, debuting with that year’s first London Mayoral election, won by Ken Livingstone standing then as an Independent. The Local Government Act 2000 gave Local Authorities the option to hold a referendum to introduce a directly-elected mayor for their Council, to replace the “leader and cabinet” system. Since then, 53 local authorities have held such referendums, but only 16 voted to introduce a directly-elected Mayor. Three of these (Stoke-on-Trent, Hartlepool and Torbay) have subsequently held another referendum to remove the position and return to “leader and cabinet” governance. A further two Local Authorities – Leicester and Liverpool – have used a change in the law made in 2007 to introduce a directly elected Mayor through a Council decision. All these directly-elected mayoral elections have been held using SV, as have the Police and Crime Commissioner elections which have taken place in England and Wales since 2012.

By our count, there have therefore been 145 different elections in England and Wales held using SV: 60 directly-elected local authority Mayoral; 81 Police and Crime Commissioner; and 4 London Mayoral elections. You can see an animated gif featuring all 145 elections to have used SV here.

58 of those 145 have been won by Labour candidates, 44 by Conservative, 7 by Liberal Democrats, 2 by Plaid Cymru, and the rest by Independents or local issue parties. One of the most famous of these Independents, and one of the few times that these elections made headlines, was at the Hartlepool Mayoral election in 2002. H’Angus the Monkey, the local football team’s mascot (AKA Stuart Drummond) stood as an Independent and beat the Labour candidate by 633 votes – his only policy being to offer free bananas to school children (he was unable to enact this due to lack of funds). More amazingly, Drummond won in a landslide to retain his position in 2005 and again in 2009, and remained Mayor until the post was abolished by referendum in 2013.

A clear majority of these elections have been won by the candidate who won the most first preference votes. In fact, there have been 29 SV elections (20%) where a candidate has won more than 50% of the vote on first preferences alone, negating the need to count second preferences. The largest first round victory was in the most recent of these elections to take place – for the directly elected Mayor of Hackney, held in September 2016 after previous Mayor Jules Pipe stood down to become a Deputy Mayor of London in Sadiq Khan’s new administration. Labour candidate Phillip Glanville gained nearly 70% of first preference votes in an election where turnout was only 18.6%.

In only 13 cases, just 9% of those 145 SV elections, did the trailing candidate going into the run-off gain enough second preference votes to overtake their opponent, perhaps undermining the argument that SV leads to markedly different results to FPTP.

The graphs below show the final two candidates in all the races where the candidate with the highest number of first preference votes did not go on to be elected.

What does this mean for the Metro Mayor elections?

Recent general- and local- election history suggests that Labour should win four of the six – Liverpool City Region, Greater Manchester, West Midlands, Tees Valley – and that the Conservatives will win the other two – West of England and Cambridgeshire and Peterborough. However, those elections were fought under FPTP and the addition of a second round of voting under SV may lead to different results. Even then though, and as noted earlier, precedent from previous SV elections is that second round run offs rarely lead to a change in the winner from the first round of voting: just 9% of the 145 SV races thus far have been won in this way.

And we have some evidence to suggest that this precedent might continue with the Metro Mayor elections this year. This is because five out of the six areas where Metro Mayor elections are being held – Cambridgeshire and Peterborough, Greater Manchester, Liverpool, the West Midlands and Tees Valley – are contiguous with the boundaries for Police and Crime Commissioners (PCCs) who have all been elected by the SV system. In all those cases, the candidate who led the first round of voting went on to win the second as well. (See graphs below).

Despite that, here at Nudge Factory we think there might be some second round winners in May. Political parties will pay more attention and put more resources into the Metro Mayor campaigns than for Police and Crime Commissioners, and turnout will most likely be higher too. So whilst we might still expect Labour’s Steve Rotherham to win comfortably in Liverpool City Region, possibly in the first round, the other races will probably go to a second round of voting. If that happens, we suspect that Andy Burnham (Labour) in Greater Manchester, and James Palmer (Conservative) in Peterborough and Cambridgeshire, are firm favourites to hold on to a first round lead and win.

We had initially singled out the Tees Valley as providing a potential upset, due to the area’s history of electing independent candidates, (H’Angus the Monkey in Hartlepool and Ray Mallon in Middlesbrough) as well as seeing a relatively high proportion of independent votes cast at council elections. However, there are now no independent candidates running, with the possible disruptor in the race – the North East Party – withdrawing after being unable to raise the required £5,000 deposit. Labour now look favourites to win.

That leaves the West of England and the West Midlands races. Both of those look like they could potentially have the ingredients for second round upsets.

Although Labour have been well ahead in the West Midlands in local, general and PCC elections, Andy Street, the Conservative candidate is running a campaign which barely mentions his party. He is running a campaign which makes the most of him being a successful businessman with strong local links, and stressing that he is not a career politician. This combination could resonate with voters as the Labour candidate, Sion Simon, is a former MP and current MEP. Couple that with Labour’s polling problems under Jeremy Corbyn and UKIP voters’ second preferences and it is possible Street could pull off a win.

In the West of England, whilst the Conservatives will be strong favourites, each of Labour, Liberal Democrats and Greens enjoy pockets of strong support. The Liberal Democrats are fielding a strong candidate in former MP Stephen Williams, at a time when his party seems to be picking up in opinion polls. If Williams makes it into the final run-off ahead of Labour, he stands a good chance of picking up enough second preference votes from Greens and Labour to sneak through and beat the Conservative candidate.

If you are interested, we have produced more in-depth analysis for each Metro Mayor contest as part of Nudge Knowledge and you can download the separate briefing notes here. (N.B. They are all due a final, April update of candidates, policies and election analysis before 4th May!)