Shadow Chancellor Oliver Letwin announced plans yesterday to "set Britain on the path to a lower tax economy".

But Mr Letwin refused to give specific pledges on tax cuts, vowing there would be "no more broken promises on tax" under him.

In his keynote conference speech, Mr Letwin said: "On the first day of the next Conservative Government I will freeze civil service recruitment.

"In the first week of that Government I will lift the controls, those wretched best value performance assessment regimes, off local government.

"And in the first month of that Conservative Government, I will deliver a Budget which will implement the James reforms, begin the thinning down of those fat bureaucracies and set Britain on the path to a lower tax economy."

This was a reference to the audit of government being carried out by David James, which has already identified £15 billion worth of savings.

Mr Letwin said commentators suggested it would be courageous to promise to cut taxes by "so much on such and such a day".

But he added: "It wouldn't be courageous at all. It would be very easy. I would say it, you would cheer, and no one out there would believe us at all.

"There have been too many broken promises on tax from too many politicians.

"The sad truth is that when we were in office we made promises on tax we couldn't keep and everybody knows Tony Blair said he had no plans to increase tax at all and then raised them 66 times by stealth.

"So no more broken promises on tax. Instead of promises, actions. Instead of words, deeds."