David Cameron is under immediate pressure to quit as Prime Minister following the vote to quit the European Union.

Despite more than 80 Tory MPs signing a letter saying Mr Cameron has a “mandate and a duty” to remain in post, scores of Conservatives now believe he cannot stay in Number 10 for long.

Hilary Benn, Labour’s shadow foreign secretary, and Nigel Farage, the Ukip leader, are among leading opposition figures who have already said Mr Cameron will have to leave office.

Mr Farage told ITV's Good Morning Britain that it was "unacceptable" for Cameron to stay on as PM while Mr Benn said it was "very hard" for him to continue.

Critics will question how a sitting Prime Minister can remain in post when more than half of the country’s voters have defied him on the biggest political decision for a generation.

However MPs from across the political divide urged Mr Osborne and his chancellor, George Osborne, to stay in an attempt to oversee a period of “calm”, saying Mr Cameron had a “mandate and a duty” to continue as Prime Minister.