Some 114,201 ballots were rejected in the first round of the London mayoral election, approximately 5 per cent of the total votes cast. This wasn’t because people were deliberately spoiling their ballots to protest about the fact that no one standing represented their views. After all, there were 20 candidates in the election encompassing a broad spectrum of opinion. No, it was because they didn’t understand the supplementary vote system, whereby you’re supposed to put a cross next to the candidate of your first choice and a cross next to your second. According to official figures, 87,214 of the spoilt ballots were discounted because people had voted for more than one candidate in the first preference column.

The way the system’s supposed to work is that if no candidate gets over 50 per cent on first preferences, all but the top two are eliminated and second choices on the losers’ ballots are then redistributed. But 327,980 of people’s second preferences weren’t counted, in most cases because they’d filled in the ballot paper incorrectly.

The rationale for this hard-to-understand system is that all the voters have an opportunity to affect the final run-off between the two candidates who receive the most votes in the first round, thereby minimising the tally of wasted votes. But the number of second preferences that were transferred to Sadiq Khan and Shaun Bailey were 192,313 and 84,550 respectively, which isn’t many, considering 624,585 people voted for other candidates in the first round. In fact, more people’s second preferences weren’t counted because they’d misunderstood the voting system than were allocated to Khan and Bailey.

At present, the supplementary vote system is used in all of England’s mayoral elections, as well as the elections for police and crime commissioners, but the government intends to replace it with first past the post, parliamentary time allowing. This should help the chances of the Tory candidate in London’s next mayoral election in three years’ time, because voters for the candidates that usually come third and fourth — the Green and the Lib Dem — are more likely to put the Labour candidate as their second choice. But it’s unlikely to make much difference, because in every London mayoral election dating back to 2000 the candidate who polled the most first preference votes has won.

No, the best reason for scrapping the supplementary vote system is because it’s so poorly understood — and because the electorate rejected a transferable vote system in the 2011 referendum. Using one method in local elections and another in national elections is a recipe for confusion. When we were members of the EU, we were obliged to use some form of proportional representation when electing members to the European parliament, but now we have an opportunity to re-establish first past the post across the board. Of course, the government in Westminster has devolved decisions on the system used for local elections in Scotland, Wales and Northern Ireland, but it can simplify things a bit.

I have a personal grudge against the system because I bet £25 that Niko Omilana, one of the independent candidates in London, would poll more than 50,000 votes. I’d never heard of him before, but my teenage children assured me he’s a huge star on YouTube, as well as being very funny. In the event, he got 49,628, just 372 votes short. I wonder how many of the 87,214 ballots that ended up being rejected because people had chosen more than one candidate in the first round included votes for Omilana? Quite a few, I imagine, given that his supporters, being young and unserious, were among the least likely to understand how the supplementary vote system works. I got bloody good odds, too.

Sadiq did a bit worse than he did in 2016, and Shaun Bailey a little better than Zac Goldsmith, so I daresay he won’t risk running for a third term. He’s 50 and I don’t suppose being mayor of London is the summit of his ambitions. He’ll want to get back into parliament and make a run at the leadership in time for Keir Starmer’s inevitable defenestration. That means that whoever the Labour candidate is in 2024 won’t benefit from an incumbency effect. Combine that with a first past the post voting system and the Tories may actually have a chance of winning in 2024. My choice of candidate would be Kemi Badenoch, the former Spectator staffer who is now Parliamentary Under-Secretary of State for Equalities. Put her up against Stella Creasy or Wes Streeting and I’d wager more than £25 on her.