This will be the first London mayoral election held via First Past the Post.
Why though? It seems like such a huge step backward to go to FPTP.
The official reason was that SV was 'overcomplicated and confusing' but ultimately its because at that point the Tories believed it would benefit them - Labour losing votes to the Lib Dems and Greens that they previously would have gotten back through preferences; while the Tories would have gotten less from the Lib Dems and then the small number of right wing independent. With the rise of Reform that balance shifts I think; especially factoring in other Mayoral/PCC elections where Reform might pose more of a risk.
Its worth noting that SV was far from perfect and almost relied on a core two party system to work as intended: in London since 2004 it allowed voters to vote for a minority party knowing that ultimately they could back their preference of the big two. However in the 2000 election it sort of posed issues for people that weren't Labour/Tory/Livingstone voters - a smart voter in those elections had some clear options (Livingstone voters probably preference Labour, the Tories I would suspect would have went for Norris over Livingstone but who knows; Labour probably more split than people think) but if you were a Lib Dem/minor party voter then you still had to think tactically about that second preference in order to make sure it counted. To give a more relevant modern example: imagine a place where the Greens are locally strong, Labour have a decent core vote and so they are roughly even and more voter blocks preference each other and the Conservatives can probably get 45% in a good year: under FPTP they win on split votes; under SV I suspect they win as Lib Dem and other votes scatter to the wrong candidate; while under AV you would see a more accurate reflection as anti-Tory Lib Dems could rank the Lib Dems, Greens and Labour in any order and their vote would naturally flow to the biggest anti-Tory candidate. Traditional AV is better in every way; it makes more sense ('rank candidates in the order of your preference, as many as you would like'); it allows voters more choice and in more complex elections it gives voters a firm ability to influence the final result no matter what.