The Prime Minister's expected resignation date has been moved forward by 1 day, from 22 September 2026 to 21 September 2026, according to the latest Polymarket data.
The change indicates the market now sees an ~86% chance Keir Starmer will step down as PM by 21 September 2026, rather than the previous date of 22 September.
This comes as the political landscape continues to evolve around the Labour leader's future.