He said Labour had displayed a "cavalier arrogance with the taxpayers' money" and accused former Ministers of behaving "recklessly" and thinking "big government" could solve every problem.
After the pomp and ceremony of the State Opening of Parliament yesterday morning – which outlined 22 Bills to be unveiled over the parliamentary session, and identified tackling the budget deficit as the top priority – Mr Cameron was in buoyant mood in the Commons as he declared: "This Queen's Speech marks an end to the years of recklessness and big government and the beginning of the years of responsibility and good government."
In his first major speech at the Despatch Box since becoming Prime Minister – with his deputy Nick Clegg, the Liberal Democrat leader, at his side – he tore into Labour's record in power and promised to govern in the national interest, giving power back to communities and tearing down state intrusion built up over the past 13 years.
When he was questioned over cuts already announced by the Government, including axing Child Trust Funds, he said the country had "run out of money" and told his Labour opponents: "You broke the nation so badly that it's schemes like these that can't be continued."
He said his plans for the first parliamentary session represented a "radical programme for a radical Government" and said the Queen's Speech – which won praise from businesses but criticism from trade unions – was the "first step" in putting things right after an "appalling legacy" left by Gordon Brown.
Promising an administration based on values of freedom, fairness and responsibility, he pointed to the creation of an Office of Budget Responsibility and the 6bn of cuts and claimed: "In just two weeks, this Government has done more for our economy than Labour managed in the last two years."
On foreign policy he set his sights on Iran vowing to "ratchet up" the pressure amid fears the state was intent on developing nuclear weapons, and said 2010 was a "vital year" for the future of Afghanistan after paying tribute to the troops serving there.
HARMAN HITS OUT OVER 55PC RULE
David Cameron got a taste of the battle ahead as Labour tore into his plans for fixed-term parliaments which would need 55 per cent of MPs to dissolve the House of Commons.
Acting Labour Leader Harriet Harman backed the idea but added: "We will not support a 55 per cent rule which would allow the Government to cling on to office having lost the support of the House. They have no mandate for that change."
Earlier Labour's acting leader Harriet Harman had promised to be an "effective" opposition but warned her party would not "pull our punches" in showing where ministers were going wrong.
"The country will want to see it is not they who are left bearing the cost of holding the coalition together," she said, mocking Mr Cameron and Mr Clegg after the way they had criticised each other during the election campaign.
"While the happy couple are enjoying the thrill of the rose garden, the in-laws are saying they're just not right for each other," she said.
"We keep telling them that you can't pay couples to stay together. It's clear it will take more than a three-quid-a-week tax break to keep this marriage together."
Meanwhile, Speaker John Bercow expressed his "disappointment" that details of the Queen's Speech had been leaked at the weekend. He reminded Conservative and Liberal Democrat Ministers they ought to make key announcements to the Commons first.