Boris Johnson has resigned as Foreign Secretary

The resignations of the two Cabinet "big beasts" comes just days after Mrs May secured senior ministers' agreement at Chequers for a Brexit plan about which both men had expressed reservations.

But there was growing speculation about Mr Johnson's plans on Monday after he failed to attend a meeting of the Government's Cobra emergencies committee as well as a summit of Western Balkan nations being held in London.

At 3pm on Monday, a statement was issued by Downing Street to say: "This afternoon, the Prime Minister accepted the resignation of Boris Johnson as Foreign Secretary. His replacement will be announced shortly. The Prime Minister thanks Boris for his work."

Staunch Brexiteer Dominic Raab was named as Mr Davis's replacement as Secretary of State for Leaving the EU.

Middlesbrough South and East Cleveland Simon Clarke MP said on hearing the news: “I was elected by people in Middlesbrough South and East Cleveland to deliver Brexit. I am the only Teesside MP who has honoured the overwhelming majority vote to Leave the EU in our area.

“When we leave the EU, it’s vital we do so in the way that is best for Britain, and not in a halfway state that compromises our control over key issues like trade and leaves us subject to the ECJ, which will be a wholly foreign court.

“The Government has set out its headline proposals, but colleagues across the House are clear that before we make any binding decision, we need to see the full Government White Paper that will be published on Thursday. I have also asked Downing Street some key questions about the ramifications of these proposals for our bid for a Freeport at Teesport.

“To be clear: I cannot and will not support the wrong deal. I was elected to help make Britain a free-trading, prosperous and independent country, and I can promise my constituents that, for as long as I am their MP, that is always what I will work to do.”