Conservative Central Office is "blocking" Iain Duncan Smith's attempts to reshape the party, a senior frontbencher warned yesterday.

Speaking to the Telegraph, Tim Yeo said the Tories were in danger of becoming complacent as a result of recent opinion polls putting them ahead of Labour.

"The party needs to let Iain Duncan Smith lead in the way that previous leaders have. At the moment there are too many elements in the organisation which act as blocks against what he's trying to do," he said.

"We mustn't assume that just because things have gone badly for Labour the country is about to turn to the Conservatives.

"We can't assume that a slump in Labour's support automatically leads to a Conservative government."