Cameron's lead bounces back to 17 per cent

Voters say Tory leader’s background does not bother them, as Brown slump takes Labour to just three points ahead of Lib Dems

The Conservatives have opened up a polling lead of 17 points, bringing an abrupt end to recent Labour hopes that the next election could result in a hung parliament.

David Cameron's party is up two points on last month, on 41 per cent, while Labour has slipped one point to 24 per cent. The Liberal Democrats are up four points on 21.

The ComRes survey for The Independent on Sunday also exposes how Gordon Brown's strategy of attacking Mr Cameron's Etonian background has fallen flat with voters.

Seven out of 10 say the Tory leader's schooling does not make it harder for him to be a good prime minister, with just 20 per cent saying it does. Even among Labour's core voters, in social group DE, only one in five says his schooling is a problem.

The poll is the first comprehensive voter reaction to last Wednesday's pre-Budget report (PBR), suggesting that Alistair Darling's measures to increase National Insurance and reduce the deficit have also fallen flat.

It follows a series of surveys where the gap between Labour and the Tories narrowed to as little as six points – which if repeated on election day would mean a hung parliament. Today's poll would give the Tories a majority of 106.

Only the Chancellor's plan to impose taxes on bankers' bonuses is backed by voters, with 66 per cent saying taxing high earners is fair. And Mr Cameron and George Osborne, the shadow Chancellor, have yet to convince voters that they have the right prescription to get Britain out of recession. Some 34 per cent agree they have the right ideas; 46 per cent disagree.

There is equivocal backing for the Conservatives' plans to give tax breaks for married couples, with the same proportion – 46 per cent – in agreement as in disagreement. However, in an apparent vindication of Harriet Harman's attack on Mr Cameron's flagship policy as a "philanderers' charter", there is a significant gender gap. Some 55 per cent of men back the married couples' allowance, compared with 39 per cent of women, while 52 per cent of women are against the plans, compared with 39 per cent of men.

There were signs of a growing rift between Mr Brown and Peter Mandelson over the tax on bankers' bonuses. Lord Mandelson has not commented on the economy for more than a week – after calling for restraint on bonuses in an interview on Radio 4's Today. There is also tension between Mr Darling and Mr Brown over the extent of Labour's spending cuts to rein in borrowing.

Writing in the IoS today, Liam Byrne, the Chief Secretary to the Treasury, tries to draw a line under cabinet rifts by turning fire on the Tories. Mr Osborne, in an interview yesterday, said it was the "number one priority" to avoid introducing the planned 1 per cent rise in NI. He said: "I will do everything I can to avoid that tax rise." But Mr Byrne demands that Mr Osborne spell out what the Tories would do instead to reduce the deficit – and within three years, not four, as the Tories have promised.

Mr Byrne says: "Mr Osborne says that he would close the deficit faster, but halving the deficit just one year faster than us would mean cutting a further £26bn from public services or increasing VAT to 23 per cent. Which will he choose?"

Mr Cameron, in an email to activists yesterday, said Labour had "lost the right to govern". He added: "Their pre-Budget report on Wednesday was an opportunity to finally confront the biggest budget deficit in Britain's peacetime history. Instead, they put their own political fortunes ahead of what is right for our country. Not only did they decide to carry on their irresponsible spending, but they're actually increasing it next year."