We have to re-establish, with millions of citizens who are very cross, our credibility as an alternative government.

Oliver Letwin

In an interview with the New Statesman magazine, the senior Conservative says his party did not learn to engage in opposition under William Hague

"We were too inclined to spot an opportunity for grabbing a headline and too exposed to having to reverse the decision later," he says.

Hard task

Mr Letwin says he was as guilty as anyone for not coming to terms with the fact that what people most want to know about an opposition is whether it can be trusted with running the country.

"We have a huge hill to climb. It is very large. We have to re-establish, with millions of citizens who are very disenchanted and very cross, our credibility as an alternative government.

"That isn't something we are going to be able to do in a week or a month or a year. It's something we have to try and do over four years."

Letwin went into hiding in the election campaign

Mr Letwin says he does not know whether that is achievable but wants his party to come out of its "long and bleak abeyance".

The outcome is not "preordained", he acknowledges, and will require Tories to eschew "yah-boo" politics.

The shadow home secretary, whose profile at Westminster has been boosted as the anti-terror plans go through Parliament, says people are not currently paying his party much attention.

Hunting Bin Laden

He hints that he believes assassination is the best way to deal with Osama Bin Laden.

"I think there are times when an enemy is so dangerous that you are entitled to kill him," he says.

The reignition of the debate over tax and public services this week recalls Mr Letwin's role in the general election.

He went into hiding from the media after being blamed for suggesting in an off-the-record interview that the Tories were aiming for a �20bn tax cut in the long-term.

In his interview, Mr Letwin says the Conservatives must show they can provide better schools, hospitals and transport without spending "a colossal extra amount of taxpayers' money".

Only then will anyone pay attention to claims that it is possible to control the growth of public spending "over time - which is all we wanted to do", he argues.