Cheered on by Labour MPs, Ed Miliband directly challenged Cabinet Ministers to admit whether they stood to gain personally from George Osborne's "millionaires' budget".
He narrowly focused his attack on the Chancellor's decision to drop the top tax rate from 50p to 45p next year, insisting it sounded the "death knell for compassionate Conservatism".
Mr Miliband claimed that a person on a £5m salary would save £240,000 a year in tax, contrasting "an income tax cut for the richest 1 per cent" with cuts to tax credits and child benefit and the increases in fuel duty faced by the lower-paid.
In raucous Commons scenes, three times he urged ministers to raise their hands or nod if they would be better-off as a result of lowering the top rate.
Quoting back one of the Government's favourite mantras, Mr Miliband said: "Sunlight is the best disinfectant. Just nod if you're going to benefit from it, or shake your head if you're not. Come on – we've got plenty of time."
He also took a swipe at Mr Cameron for borrowing a horse loaned by the police to the former News International chief executive, Rebekah Brooks. Mr Miliband told him: "Now you're going to be able to buy your own horse."
The Labour leader went on to lambast Nick Clegg, the Deputy Prime Minister, as a "hapless accomplice" to the plans, mocking the Liberal Democrats for going from "following Lloyd George to following George Osborne".
The former Tory Cabinet minister, John Redwood, argued the Treasury would be able to raise more revenue by cutting the top rate to 45p and pointed out that in all his time as Chancellor Gordon Brown chose never to increase the tax level.
"Even Labour would accept that if you put the rates too high, [top rate taxpayers] go away. They find ways round it, they don't pay the tax," Mr Redwood told MPs.
Stephen Williams, a Liberal Democrat treasury spokesman, said the party had achieved its key objectives. He said: "We wanted to see a fair income tax system that lifts the low-paid out of tax and brings about a tax break for middle earners.
"We wanted a tax system that taxes accumulated and unearned wealth fairly and effectively and we wanted action to tackle abuse of the tax system through aggressive schemes of tax avoidance."
Referring to the new seven per cent stamp duty on house sales of more than £2m, he said: "We may not have got a mansion tax in this Budget, but we have certainly got a mansion duty."
The former Labour Cabinet minister, John Denham, highlighted moves to freeze tax relief for existing pensioners and reduce it for future retirees. He said: "I suspect that the detail of the pensioner tax changes will come as a deeply unpleasant surprise to Members opposite who were waving their order papers so cheerfully earlier on."
Andrew Tyrie, the Tory chairman of the Treasury Select Committee, warned Mr Osborne that it would investigate how much of the Budget had been pre-briefed to the media.
"I have to tell the Chancellor that several colleagues on both sides of the House have complained to me about the leaks and the briefings in the days prior to this Budget," he said.
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