UK Prime Minister Keir Starmer announced his resignation shortly after 09:30 BST on Monday, confirming that a new leader would be in place by 1 September - though it could be sooner if there's no contest.
In an emotional speech, he paid tribute to his family - and later in the evening, Starmer and his wife, Victoria, hosted drinks for staff in the No 10 garden.
Meanwhile, Andy Burnham - after boarding a train from Manchester Piccadilly to London Euston to be sworn in as MP - announced his intention to run to replace Starmer - but told the BBC it was too early to think about calling an election
By this point, the former Greater Manchester mayor had gained the support of former health secretary Wes Streeting, and was later pictured surrounded by hundreds of Labour MPs at Westminster Hall
So far today, the big question is - who will be the next PM and how should they be chosen?
Darren Jones and Al Carns are weighing up whether to challenge Burnham, but, for now, it feels unlikely either would get the required 81 nominations, says our chief political correspondent
Some Labour MPs have been calling for a contest, while others say it's important to get a new team in place quickly
Ministers have been at Downing Street this morning for the first cabinet meeting since Starmer's resignation. The mood in the room will have been radically different, writes Henry Zeffman
As Keir Starmer prepares to leave Downing Street, there is speculation that his Chancellor Rachel Reeves may follow him - if Starmer's successor opts for someone new. Here's some of the names believed to be in the running for the job.
Wes Streeting: Instead of pitching himself for the leadership role, Streeting has backed Burnham and could be awarded the number two job in British politics for his loyalty.
Ed Miliband: Some see Miliband as an inflation risk, believing his drive for net zero as energy secretary is partly responsible for the UK's high energy prices compared to other countries. But others think he could gain the confidence of the markets with his "intellect, experience, and authority".
Pat McFadden: He's held shadow Treasury jobs, been a business minister in a Labour government and is the current work and pensions secretary. His experience in the latter could help tackle welfare reform.
Yvette Cooper: She has years of experience in government, and served as chief secretary to the Treasury under Gordon Brown.
Former defence minister Al Carns says he has not ruled out launching a leadership campaign and the decision is based on "multiple factors".
Speaking to journalists at the Foreign Press Association in London, he says: "I just need to see and buy into that vision and that policy and then we’ll see where we go from there."
Carns says Burnham would "listen" to the Parliamentary Labour Party and "he’ll take advice on policy ideas".
"And hopefully he’ll be able to drive them forward at a pace and with the boldness and courageousness that is required to keep that social cohesion and make us successful in the 2029 general election."
But he adds: "A vision without a plan is a dream and if you don’t have it, it can turn into a nightmare pretty quickly."
