General Election 2010: Ken Clarke spoiling for a fight with 'Prudence'

• Kenneth Clarke gives Cameron's campaign the benefit of his decades of experience. Photograph: Jane Barlow

"He is the only person to deliver a financial crisis in the middle of a boom." You didn't get much in the way of red meat from David Cameron last week during his muted performance during the Prime Ministerial debates, but Ken Clarke has no such scruples.

The former chancellor is holding court in what must rank as his perfect interview venue; the beer garden of Edinburgh's famous Canny Man pub, pint of heavy on the table, full box of cigars in his suitcase. The 69-year-old Clarke makes the craggy Vince Cable – a good friend, incidentally – look like well-polished choirboy. He looks like he has slept on his suit, never mind in it.

The similarities between Clarke and Cable are many, but with one big current difference. While Cable is the Lib Dem shadow chancellor and has been welded onto the side of Nick Clegg during this campaign, Clarke is the Tory shadow business secretary and has not been nearly so high profile. This weekend, that campaign is having yet another wobble following the TV debates last week, which saw Clegg's surge suddenly threaten a Tory majority. So why, with the public mood so cynical, aren't trusted old-stagers like Clarke front-and-centre of David Cameron's faltering ascent to the peak?

Clarke dismisses the question's premise, insisting he is being used a lot. But he adds: "I feel a bit like, in footballing terms, the veteran striker on the bench waiting to be called on." And from that bench, he adds, he sees one of the oddest campaigns in his 40-year political career. "People realise it is a very important election but at the same time they are turned off and detached from it and cynical and suspicious," he declares. "And that is probably why we are not further in the lead against a completely demoralised government. People are not prepared to get highly inspired or totally trusting of anything. I can't remember an election where I've felt pretty sure we are going to win but I have detected a wariness and a detachment on the part of the electorate."

An ageing super-sub he may be, but Clarke is raring to have another go back in government, and is keen to talk about the challenges an incoming Tory government would have, as it seeks to haul down Britain's vast deficit. Compulsory redundancies would be avoided where possible, he insists. Tackling waste would be the main aim. "I've been through more public spending rounds than most people have had hot dinners," he notes. It seems wily attempts by civil servants to avoid the axe will not pass Clarke's beady eye. In his own patch, as shadow business secretary, he says he backs the Tory plans to tax the banks. "The public is entitled to say that taxation to recover some of the banks' profits is called for," he argues.

The socially liberal Clarke is said to be less approving of the fact that some of that cash will be used to pay for the Conservatives' marriage tax allowance. Clarke insists in truth he's not that bothered. "It (the allowance] is also tended to civil partnerships as well, so it is not loaded with the moral overtones, which some of the advocates wanted it to have."

Clarke argues that, in such a big ticket election as this one, smaller parties such as the SNP are an irrelevance – though he hopes that this doesn't offend Alex Salmond.

"I know Alex and I get on with him well personally," he says. "He is the most skilled populist campaigner certainly in Scottish politics. But there is no doubt that he is an incorrigible short term populist."

In a grave national crisis – such as that which Clarke sees heading our way – he believes a strong majority government at Westminster is required. "One of the most disastrous outcomes of this election would be a hung parliament. In fact, the worst outcome of all would be a hung parliament," he argues. The world is watching, he says, to see how Britain gets itself out of this mess. "We are there in the same position as Greece, Spain and Portugal, and if the British electorate produced a hung parliament with several smaller parties negotiating short-term positions of their own as their condition for having a government that could cause another round of financial problems of quite a serious nature."

Salmond and new kid on the block Nick Clegg would disagree with that, of course. But even they would be hard pressed to beat Clarke in a debate. As the pint of heavy sinks down, Clarke launches into a magnificent rant at Gordon Brown. "Gordon Brown has delivered a train crash," he rages. "It's not some funny event that happened in the mid-west of America. It was the madness of bankers on Wall Street and in the City of London to whom he (Brown] was giving knighthoods and it was a regulatory system that he wrecked.

"It was this stupid tripartite system and a giant Financial Services Authority that wasn't even looking at the mismanagement of the banks. He (Brown] completely wrecked the public finances before the credit crunch even started. He is the only person to deliver a financial crisis in the middle of a boom. If he had stuck to my figures, he would have run up an enormous budget surplus; an excessive surplus. It is his fault."

David Cameron is said to be considering a more aggressive approach for the next leaders' debate on TV this coming Thursday. Copy and paste.