The morning Gordon made David choke on his porridge

The Tory leader's getting angry and he's turning up the volume – lambasting the Prime Minister as a headless chicken and the House of Lords for its toxic cocktail of money and politics

"I choked on my porridge this morning," David Cameron said. He wasn't joking about his favourite breakfast food at his family's regular 7.30am start to the day in Notting Hill, west London. What stuck in his throat yesterday was a newspaper report of Gordon Brown describing the economic crisis as "the birth pangs of a new global order."

The Tory leader is still angry about it six hours later when The Independent interviews him in his Westminster office overlooking the river Thames. The Brown Government, he declares, is "in a state of denial" about the economy. "Imagine how you would feel if you had just had your home repossessed, lost your job or couldn't get credit: 'It's all right, I'm just a birth pang.' It was a bit of a moment."

Mr Cameron accuses Mr Brown of "behaving like a headless chicken" and "an opposition rather than a government" as he rolls out economic initiatives almost daily. "There is a sense that the Government is thrashing around wildly, throwing stuff out, hoping something will stick. That is not good for confidence or the economy," he says.

"It is confusing activity with action. What people want is strong, bold and straightforward action on the things that matter. Instead, they get initiatives. It doesn't work because things are not followed through, and adds to the sense of fear and panic because it helps to undermine confidence."

For once, Mr Cameron's main theme is not the economy but how to clean up the House of Lords. Across the board, he wants to avoid repeating Tony Blair's mistake of over-promising. On this issue, he admits he would not deliver overnight a "nirvana" of squeaky-clean politics in which everyone wears "halos".

But he does pledge a better system so that inevitable problems stemming from the dangerous cocktail of politics and money are "found out and rooted out". He adds: "We have to be realistic. Money and politics is like water running down a street. It always funds a crack in the pavement. We have to be perennially vigilant." The Lords, he argues, is the weak leak in the chain. MPs have put a lot of effort into cleaning up the Commons, but not the second chamber, despite its extensive work on revising legislation and influence, because Labour does not enjoy an overall majority in the Upper House.

He said tougher rules would in future cover promises by those awarded peerages, such as to live in Britain and pay taxes here. This is potentially tricky territory. Lord Laidlaw, a Tory donor, had the party whip withdrawn after failing to honour his commitment to bring his tax affairs back to Britain. Lord Ashcroft, who remains a donor and a Tory deputy chairman, made a similar promise. What about his tax status? "You can ask him. I'm sure he will tell you," says Mr Cameron. (In fact, he won't, since his spokesman always argues that it is a private matter.)

The Tory leader is proud he cracked down on MPs' expenses before Labour, persuading all but four of the 193 Tories to voluntarily publish the details of their claims. Now he is trying to keep ahead of the game on the Lords by setting up a task force to produce reforms to bring it into line with the Commons.

However, his drive to clean up politics will stop short of imposing a ban on Shadow Cabinet members holding outside paid jobs after a rebellion led by William Hague, the shadow Foreign Secretary. "What matters is: are people working, performing, putting the hours in, doing the job. If we win the election, everyone will immediately be subject to the ministerial code," he insists.

"Cash for questions" bedevilled the last Tory government led by John Major. Now "cash for honours" and this week's "cash for laws" have engulfed Labour. "If Labour cried 'Tory sleaze' now," he says, "I think people would laugh at them."

He is worried that Mr Brown is using too many peers in important ministerial posts, citing four heavily involved in handling the banking crisis – Lord Mandelson, the Business minister Baroness Vadera, the City minister Lord Myners and the Trade minister Lord Davies. Although he intends to bring more peers on to his front bench, Mr Cameron insists: "If all the ministers making the decisions are in the House of Lords, that is not good for democracy."

Despite his growing feeling that time is running out for the Brown Government and two opinion polls this week putting the Tories 15 and 12 points ahead of Labour, Mr Cameron is taking nothing for granted. His warnings against complacency were vindicated when Mr Brown, written off by many in his own party, staged a remarkable fightback last autumn after saving the banks.

Although he now says Mr Brown's "hubris" over the first rescue was a mistake, Mr Cameron admits that at the end of last year, he believed the "Brown bounce" in the polls was so real that the Prime Minister might be tempted to call a general election next month "to trade on people's anxieties" in the recession.

Now the Tory leader appears to expect a 2010 poll, while insisting he will be ready at any time. "There is a very long road between now and whenever an election is called," he says revealingly. "You have to be ready. That is my job," he says. "I, my Shadow Cabinet, my party have to prove we would do better, have better ideas, would be a stronger team." It's not just about the economy: he promises that Tory thinking on health and education will be threshed out in the coming months, even if there is no election.

Mr Cameron is convinced his team is stronger after last week's Shadow Cabinet reshuffle. He is delighted that Kenneth Clarke, the shadow Business Secretary, is back after an 11-year absence from the front bench. It is a huge asset, he believes, to have in his team "the last Chancellor to lead us out of recession".

To his relief, even hardened Eurosceptics in his Witney constituency in Oxfordshire came up to him in the street last weekend to welcome his decision to recall Mr Clarke. They don't agree with the Clarke view of Europe, but were delighted to see him back where he belongs.

Like everyone at Westminster, Mr Cameron's eyes are on Washington. Shrugging off Labour claims that he is isolated on economic policy around the world, he insists: "Because Barack Obama is not having an immediate election, he is able to take the right long-term decisions. A new government in Britain would be able to take the right long-term decisions.

"The whole focus is on what the Conservative Party has to do to deserve to win. There is no such thing as a moment when politics has suddenly fundamentally shifted. You have got to keep working at making sure that when it comes to the election, you can look the British public in the eye and say we have the right policies, approach, character and judgement to take the country forward."

'It's 1.25 and I've met Ken three times already'

"I've had three meetings with Ken Clarke already today and it's only 1.25pm," David Cameron said. They were his daily 9.15am "council of war"; a meeting about the Government's package for the car industry and a session on the banks which also included George Osborne and Oliver Letwin.