Conservative MPs will get a “wake-up call” from party members when they discover the extent of support for Andrea Leadsom, the head of the voluntary party has said.

The news came as it emerged that the Tory party’s membership has swelled in size since David Cameron quit, with 10,000 new members joining in the four days after his resignation.

Steve Bell, the president of the Conservative Party’s National Convention, which represents the party’s voluntary associations, said he was “expecting” Mrs Leadsom to win.