Why Liz Truss will need to meet King Charles and how the new UK Prime Minister will be decided

Six weeks ago, Liz Truss met with the reigning monarch to seek permission for the formation of a new government.

It could not have been a scene more different from the one that greeted the outgoing Prime Minister this afternoon.

Standing behind a lectern outside the famous black door – a scene that has become extremely familiar in the last few months – she admitted her mandate to govern was in tatters.

It means the starting gun has been fired on a second Tory leadership contest in the space of a few months.

Sir Graham Brady, chairman of the party’s 1922 committee, said he was confident a replacement would be in post before the Office for Budget Responsibility fiscal report is released on October 31, there are still a few more steps before a successor can be confirmed.

What happens now?

Liz Truss will still have to meet the King in person to formally tender her resignation.

This will take place immediately before the monarch asks her successor, also in person, to form a government.

It was exactly what Boris Johnson did prior to Truss taking over shortly before the death of the Queen.

That meeting took place at the Balmoral Estate in Aberdeenshire in a slight break from tradition.

Charles as sovereign plays an important constitutional role in the appointment of a new prime minister.

Why does Liz Truss have to meet the King?

The Royal Encyclopedia states that the appointment of a prime minister is “one of the few remaining personal prerogatives of the sovereign”.

It says that, in the normal course of events, the monarch does not act on advice nor need to consult anyone before calling upon the leader with an overall majority of seats in the House of Commons to form a government.

But the monarch is guided by constitutional conventions and can seek advice from the outgoing prime minister, any other political leader, senior privy counsellors, or whomever they please within the limits of prudence and caution.

The King spoke to Liz Truss on the phone, when she informed him she was resigning, the same day as holding the first credentials presentations of his reign at Buckingham Palace.

Credentials presentations are audiences with newly appointed ambassadors or high commissioners who hand over their letters of credence or commission to the monarch.

Will there be a vote?

Truss said she would remain as PM in the interim, but made the bold claim that a new incumbent would be chosen “within the next week”.

That has triggered another leadership election, though the rules of this one are yet to be announced.

Usually, there would be several rounds of voting to allow candidates to secure enough backing to make the final shortlist before elimination votes led to a run-off between the final two.

It is unclear what shape this vote will take, but after that finishes, it is all back to the monarch’s for the final go-ahead.