London mayoral race: Will Rory Stewart’s candidacy ‘split’ the Conservative vote?

Doug Cowan
Author:
Doug Cowan

Posted on the 4th October 2019

If there is one thing you can predict about politics these days, it’s that you can’t predict anything. In the space of a few months, Rory Stewart has gone from running for leadership of the Conservative Party, to having the whip withdrawn and then announcing he’s standing down at the next election. The latest twist is that he’s going to stand for Mayor of London as an independent.

There have already been predictions that his candidacy as an independent will ‘split the vote’ of the official Conservative candidate Shaun Bailey, allowing Sadiq Khan to win an easy re-election.

But it’s worth remembering that the mayor of London is not elected using the Westminster style First Past the Post system. First Past the Post is a terrible way of electing people as there is no guarantee that the winner will get anywhere near the support of half the voters.

Using the first past the post system, all it took was the support of one-quarter of the voters to elect the MP for Belfast South in 2015. That means that someone 75% of the voters didn’t want could vote on their behalf in Parliament. In many seats across the country, MPs are often picked as the sole representative of an area simply because the opposition was slightly more divided than their own side.

The Mayor of London is a very powerful position, so it’s important that the winner is the person that most Londoners want. That’s why Mayors (and Police and Crime Commissioners) are elected using the Supplementary Vote.

This electoral system is part of a broad group of ‘preferential’ (or ‘ranked choice’) voting systems, which include the Alternative Vote used in Australia. It’s also fairly similar to the ‘rounds’ system in which the Conservatives elect their leader, but condensed down to one ballot paper.

With the Supplementary Vote, everyone has one vote – just like with First Past the Post. But voters can also write down a backup ‘supplementary’ choice. All the votes are counted and if one candidate gets over 50% they are elected.

If no candidate gets over 50%, the top two candidates continue to a run-off round. If you voted for a candidate who didn’t get through to the run-off, your vote gets moved to your back up choice. They then count up the votes again. The candidate with the most votes at this stage is declared the winner.

The impact of this is that centre-right voters (such as Conservatives) in London can vote for Rory Stewart in the knowledge that they can, for instance, put Tory candidate Shaun Bailey as their second choice – and their vote won’t go to waste if either get through to the second round.

One of the downsides of the Supplementary Vote, compared to the Alternative Vote (where you can rank more than two candidates), is that it all depends on getting through to the second round.

Shaun was in a solid second place in the last mayoral poll in Dec 2018. However, this was before the general dip in Labour’s polling position, which only really started to happen in the early part of 2019. It was also before the rise in support for the Liberal Democrats seen at the European Elections.

If Rory ‘takes’ enough first-choice ‘Shaun votes’ to make the latter drop to third place behind either the Lib Dems’ Siobhan Benita or the Greens’ Siân Berry, it doesn’t matter that Rory voters have put Shaun as their second choice – he will have been knocked out. Likewise, if Rory beats Shaun in the first round, but still comes third overall, it doesn’t matter that Shaun’s voters put Rory second: again, the latter will have been knocked out.

Supplementary Vote encourages a form of strategic voting where the most logical thing to do is to cast your first choice for your genuine favourite candidate, and your second choice for your preferred candidate that you think will make it through to the run-off.

But this kind of second-guessing becomes more difficult as the number of candidates increases – in particular in races where multiple people may enter the second round.

A fully preferential system such as the Alternative Vote would allow voters to put more than a first and second choice down, increasing the chance of their vote counting and ensuring they will have a say in who’s elected.

Image: Flickr: Foreign and Common Wealth Office

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