But that was under the supplementary vote (SV) system. Last year, the Elections Act 2022 – more noted for its controversial voter ID requirement and attempts to rein in the independence of the Electoral Commission – replaced SV with first past the post (FPTP). The government dropped this change into the bill late in the day, with opposition from Labour muted at best, with the opposition preferring to concentrate their parliamentary fire on the introduction of voter ID.

https://www.instituteforgovernment.org.uk/comment/elected-mayors-first-past-the-post