How soon will a contest begin?

Mr Starmer said he wanted nominations to open on July 9 for the Labour leadership.

Labour’s rules mean getting onto the ballot can be a complex process, with candidates requiring the backing of 81 MPs, 20% of the party’s parliamentary strength.

The British prime minister said he wanted the nomination process to be completed by the time Parliament breaks up for the summer.

If Andy Burnham – whose return to Westminster hammered the final nail into Mr Starmer's political coffin – is the only candidate, he could become prime minister by the middle of July.

What if there is a leadership election?

If there is a contest, the new leader will be in place by September 1, when MPs return to Westminster.

To compete in a contest, having secured the required support of MPs, they need to receive nominations from either 5% of constituency Labour parties, or three affiliated organisations (which must include two trade unions) which represent 5% of affiliated membership.

Only after passing those two stages will candidates go before the party membership.

Labour’s ruling national executive committee (NEC) will meet shortly to agree the timetable for the contest.

Could anyone stand against Andy Burnham?

Former British health secretary Wes Streeting has repeatedly insisted he has the 81 names required to mount a leadership bid, and has spent the weeks since his resignation setting out his stall.

Former Royal Marines officer Al Carns, who quit as armed forces minister in a row over defence funding and the treatment of Northern Ireland veterans, has also hinted he would seek to enter a leadership race, although it is unclear whether the MP – who was only elected in 2024 – has the supporters required to get on the ballot paper.

What happens to Keir Starmer now?

He remains prime minister until Britian's King Charles appoints his successor.

Mr Starmer is expected to represent the UK at the Nato summit in Turkey which starts on July 7, appearing alongside other world leaders including Donald Trump at a time when his own authority as prime minister has evaporated.

The prime minister’s final act on the international stage could be at the UK-EU summit on July 22, with efforts to repair relations with Brussels forming a key part of his political legacy.

What will Starmer do next?

There has been widespread speculation he could be offered an international role, either as foreign secretary or in some other capacity.

But in his resignation speech, Mr Starmer appeared to indicate he will be spending more time with his wife, Lady Victoria Starmer, and their two teenage children.

His voice choked with emotion, he said: “When I leave the biggest job in the country, I shall spend more time on the most important job: being the best husband I can to my fantastic wife, Vic, who has been a rock by my side through good times and bad, and being the best dad I can to my beautiful children, who are my pride and my joy.”