'This is the best tonic for Britain'

Gordon Brown went on the offensive today in his bid to convince voters that they should pay billions more in tax to rescue the National Health Service.

Only a day after announcing rises in National Insurance contributions which will cost a £40,000 middle-income earner £450 a year from next year, the Chancellor and Tony Blair attempted to focus taxpayers' minds on how the money would be spent.

Mr Brown today acknowledged that he had taken a massive "political gamble" with his £8.5 billion-a-year tax-raising Budget. He also refused to rule out the prospect of yet more tax rises in future Budgets to shore up public services. Mr Brown denied that his Budget represented a U-turn to old Labour tax and spend.

But he said: "Yes, it's a gamble politically but it's not a gamble with the economy, because the economy is stable. I don't think I'm nervous because I think it is the right thing to do." Voters had been offered "a hard and difficult choice", added Mr Brown, but he went on: "I want the best health service and so do the British public."

The Tories, meanwhile, accused Labour of breaking its pre-election promises not to raise tax on people's incomes and using "sleight of hand" to try to disguise the effect of the 1p rise in National Insurance for all.

They focused on tables showing that while those on average incomes would be about £150 a year worse off, partly offset by benefit changes, the extra charges increased further up the income scale. Top earners on £100,000 face extra tax bills of about £1,000 from next April. Many employers, meanwhile, hit out at Mr Brown's move to make them pay the same extra National Insurance as their employees, branding it a "tax on jobs".

However, changes to the benefits regime will bring relief to millions of middle-income households. Those earning up to £50,000 will receive payments worth up to £1,400 a year. The payments will then be progressively reduced up to a cut-off point of £58,000 household income.

With the full effect of the Budget changes still sinking in at workplaces and homes across Britain, the great debate was: would voters be convinced of the need to pay? Mr Brown has effectively gambled Labour's hopes at the next election - and his own ambition of taking over from Mr Blair - on the NHS starting visibly to improve in the next three or four years.

He has risked blowing apart the coalition which has delivered his party two successive landslide victories, which allied traditional Labour voters with middle-class electors wooed by the pledge not to raise taxes. The last time Labour went into an election specifically declaring it would raise direct taxes, in 1992, Neil Kinnock led his party to a surprise defeat. Many Labour backbenchers, however, are not concerned about the prospect of a return to the party's tax-and-spend roots.

Health Secretary Alan Milburn, meanwhile, was setting out detailed NHS reform plans to MPs, including the first independent audit of its spending. His Commons statement was the first detailed attempt by the Government to show that tax rises would be used to fund a properly-equipped 21st century health service.

Reform plans include new financial incentives for hospital performance, more managerial freedom for top-performing hospitals and trusts, powers to be devolved to frontline staff and "increased choices" for patients.