Recent political instability in the UK, including Keir Starmer's June 2026 resignation amid Labour losses in the May local and Scottish Parliament elections, has triggered multiple parliamentary vacancies through resignations, health-related departures, and moves to devolved assemblies. Confirmed 2026 by-elections in seats such as Gorton and Denton, Aberdeen South, Makerfield, and the upcoming Clacton contest reflect these pressures, with additional vacancies possible from ongoing leadership transitions or standards investigations. Traders price 6 or 7 by-elections highest because historical mid-term patterns and the current parliament's volatility support this range, while the narrow spread between those outcomes stems from uncertainty over further MP exits before year-end. Additional resignations tied to internal party dynamics or unexpected vacancies could push totals higher, whereas fewer developments might favor the lower end.