Andy Burnham’s July 2026 installation as prime minister after Keir Starmer’s resignation has anchored trader expectations around limited further turnover through 2027. Labour’s large Commons majority gives the new leader breathing room, while the next general election need not occur until late in the period, reducing immediate pressure for another handover. Historical volatility since Brexit has already produced multiple short-lived premiers, yet the market’s 85.5% probability on a total of two prime ministers reflects the view that Burnham’s early consolidation and party discipline make an additional change by year-end 2027 unlikely absent major policy failures or economic shocks. The slim 14% chance of three and negligible odds on four or more price in only tail-risk scenarios such as a sudden leadership challenge or early election.