Recent UK parliamentary by-elections have been triggered primarily by MP resignations linked to party leadership contests, standards investigations, and health or career moves. Keir Starmer’s resignation from Holborn and St Pancras on 1 September 2026 followed Andy Burnham’s entry to Parliament via the June Makerfield by-election and subsequent Labour leadership change; the writ for the 8 October contest has already been issued. Earlier, Nigel Farage resigned Clacton in July amid a parliamentary standards probe, prompting a Reform-held by-election on 13 August that major parties largely boycotted. By convention, the party holding the seat typically controls the timing of the writ once a vacancy arises. Trader focus now centers on which MPs or parties may next create vacancies before the next general election, influenced by ongoing internal party pressures, potential further leadership strains, and any new standards cases or personal circumstances.