Speaking to The Telegraph, Mr Bridgen, who chairs the Commons regulatory reform committee, said: “Whether he wins or loses this referendum, David Cameron is probably finished as party leader.

"If the country votes to leave the EU, he should - and probably will - choose to resign. But his Project Fear has infuriated Conservative colleagues so much that if the result is a vote for Remain, he will almost certainly face a vote of no confidence.

“There will easily be 50 MPs who will write letters of no confidence to the chairman of the 1922 committee,” he said.

“We will have to have a new leader and he or she will need to go to the country to get a fresh mandate and a bigger majority. We could be looking at a general election before the clocks go back in the autumn.”

Mr Bridgen added: "This is more important than political parties or individuals' careers. It is about the very future of our country."