Andy Burnham’s installation as prime minister in July 2026, following Keir Starmer’s resignation amid Labour infighting and poor local results, has produced unusual stability. With Burnham enjoying positive net favourability, Labour leading polls, and no early general election planned before the 2029 deadline, traders see little prospect of another leadership transition or snap contest through the end of 2027. This consensus underpins the dominant 89.5% probability on exactly two prime ministers serving by that date. A third would require either an unexpected party revolt or electoral defeat, outcomes markets currently price as remote given the current government’s polling edge and the opposition’s fragmentation.