Dominic Cummings, Iain Duncan Smith's former director of strategy, resigned three weeks ago because the Tory leader rejected his plans for sweeping reforms.

An ally of Cummings said: "Dominic believes that centre-right parties need nothing short of a revolution, a complete transformation of how they operate.

"He feels those at the top of the party do not understand the scale of the problem they face and are incapable of taking the action necessary."