BORIS Johnson will resign as the Prime Minister of the United Kingdom, he has confirmed.

The Tory leader made the announcement at a Downing Street press conference following more than 50 resignations from his government. 

He was flanked by a small number of MPs, including loyalists such as Scottish Secretary Alister Jack, Culture Secretary Nadine Dorries and Jacob Rees-Mogg, the minister for Brexit opportunities.

The National:

Acknowledging he had lost the confidence of his MPs, he said the "herd instinct" among the Tory party had moved against him - which was widely understood to be a dig at his colleagues who abandoned him in droves in recent days.

The timetable for a new Conservative leader will be announced next week, he said.

He said he and his newly appointed Cabinet will remain until a new leader is elected. 

It could be as late in the year as October until Johnson steps down, if a full leadership election is held within the party. 

But he faces the threat of a no-confidence vote in the Commons, if Labour follow through on their threat to try to oust the Prime Minister with the support of Tory rebels. 

“It is clearly now the will of the parliamentary Conservative Party that there should be a new leader of that party and therefore a new prime minister,” he said.

“And I’ve agreed with Sir Graham Brady, the chairman of our backbench MPs, that the process of choosing that new leader should begin now and the timetable will be announced next week.

“And I’ve today appointed a Cabinet to serve, as I will, until a new leader is in place.”

READ MORE: Boris Johnson resignation speech drowned out as Steve Bray blasts 'Bye Bye Boris'

In a statement released before the Prime Minister's announcement, the Home Secretary vowed to stay in her role, saying: "At this critical time my duty is to continue to lead this Great Office of State, to protect our national security, and keep the citizens of our country safe."

In a defiant statement which included a number of barbs against his critics, he suggested it was "eccentric" for them to have moved against him.  

Insisting his Government had achieved "so much", Johnson said the Tories were doing well "after quite a few months of pretty relentless sledging and when the economic scene is so difficult domestically and internationally".

He added: “It’s painful not to be able to see through so many ideas and projects myself.

“But as we’ve seen, at Westminster the herd instinct is powerful, when the herd moves, it moves.

“And my friends in politics, no one is remotely indispensable and our brilliant and Darwinian system will produce another leader, equally committed to taking this country forward through tough times.”

Speaking before the announcement, Labour leader Keir Starmer said: "If [Tory MPs] don’t get rid of him then Labour will step up, in the national interest, and bring a vote of no confidence because we can’t go on with this Prime Minister clinging on for months and months to come.”

First Minister Nicola Sturgeon has said it would be "incredible" for Johnson to remain in post, saying he must go "today". 

More to follow