It's been a big day in UK politics, not entirely unexpected, but very significant nonetheless with Sir Keir Starmer announcing his resignation as leader of the Labour party which means he will no longer be PM once a new leader is chosen. Let's take a look at how the day has unfolded. Sir Keir Starmer announced his resignation at 10 Downing Street and unveiled a timeline for his replacement. Sir Keir was the UK's sixth prime minister in 10 years and had been in the position for two years.