Labour has held the Holborn and St Pancras seat in a parliamentary by-election, defeating Green Party leader Zack Polanski in the first major electoral test of Andy Burnham’s premiership. The contest, held on 8 October 2026, followed the resignation of former prime minister Sir Keir Starmer, who had represented the north London constituency since 2015. Starmer stepped down as an MP on 1 September after leaving Downing Street earlier in the year; he was replaced as Labour lead