Gordon Brown stood accused last night of treating voters as "fools" after setting out his reasons for killing off the chances of an autumn election.

The Prime Minister said he ruled out a snap poll so people the could see his "vision" put into action, adding it was not likely he would go to the country before 2009.

But Tory leader David Cameron said the PM was "not being straight" with the public and had been pushed into his decision by polls showing he could lose his Commons majority.

And the Labour Party's deputy leader, Harriet Harman, conceded that the episode could have damaged the Prime Minister, telling the BBC: "We'll see".

His weekend announcement that there would be no November election ended weeks of fevered speculation at Westminster - but also opened an angry political row.

Mr Brown's final decision coincided with a series of polls showing the Conservatives forging into a lead on the back of their party conference and popular plans to cut inheritance tax.

The most striking - by ICM for the News of the World - put Mr Cameron's party six points ahead in 83 marginal seats, on course to depose 49 Labour MPs and force a hung parliament.

The Prime Minister, in an interview with the BBC recorded yesterday to make the announcement, insisted he had not feared defeat and felt Labour would win "today, next week or weeks after".

"The question I asked myself in the end was a more fundamental one -why am I in public life; what am I here to do?," he told BBC1's Andrew Marr Show in the interview aired in full yesterday. "And I think I have a duty to set out my vision for the future."

Asked why he had allowed the speculation to continue, he said he also had a duty to consider all requests for an early election - whether from his own advisors and MPs or the Opposition.

"There were people who were saying that you should go, there were people saying that you shouldn't go. But you know, I made the decision for a different reason.

"The decision I've made is because I want to get on with the job of change in this country. And I believe I've got to show people that we're implementing the changes in practice."

Asked if he could now rule out a poll next spring or autumn as well, Mr Brown said: "I think it's very unlikely that this will happen in the next period.

Mr Cameron told the BBC: "Watching that interview, I think people sitting at home will think 'he's just not being straight with me, he's treating the British people like fools'.

"Everybody knows he wanted to have an election and he is now saying 'I am not having an election because I want to make my changes'. But everybody knows he's not having an election because he thinks there is a chance of losing it."

Liberal Democrat leader Sir Menzies Campbell said the "charade" had been conducted entirely in the interests of the Labour Party and accused the PM of reverting to "the worst of Blairism".

"It is deeply, deeply damaging to him and more than that it is deeply, deeply damaging to politics," he told BBC1's Politics Show.

His party will today launch a bid for legislation to strip Prime Ministers of the right to pick election dates by imposing four-year fixed-term parliaments.

Labrookes said the odds on the Tories winning the most seats at the next General Election had been cut from 13/8 to 6/4.