The Guardian (
https://www.theguardian.com/politic...-voting-system-after-labour-mayoral-victories) reports that the government plans to change electoral law so that future mayoral elections use the "first past the post" system in place of the supplementary vote system currently used.
One outcome being that it makes it easier for a Conservative candidate to win in, say, London. Sadiq Khan won 'comfortably" in London this time round, but the contest would have been much closer under "first past the post".
As the article observes, a fragmented "left" means that many voters voted for other candidates as their first preference vote, with Sadiq Khan then as their second preference. Of course, the article doesn't credit the voters with intelligence to switch their voting patterns in the light of the electoral system used. It also observes that almost 5% of the ballots cast in this year's London mayoral election were rejected, mainly because voters had voted for too many candidates, so it would appear that a significant number of voters weren't able to complete the ballot properly, or chose not to for other reasons. I have previously complained to the Electoral Commission and others about the poor wording on the instructions for the postal vote for the supplementary vote system, to no avail.
For what it's worth, the change to the voting system is also planned for the elections for police and crime commissioners.
It looks as if the Conservative party is using its current large majority in parliament to prop up its future vote by changing the voting systems in its favour while it can.