David Cameron had intended to announce his Shadow Cabinet reshuffle last week - but he had to delay it because Ken Clarke was birdwatching in Panama. The harpy eagle, the flame-rumped tanager and the golden-headed quetzal were clearly more important to the former Chancellor than being promoted to the Tory front bench.

Until now, the Conservative Party's favourite “big beast” has preferred roaming the Central American rainforest to charging through the Westminster jungle. For years he has seemed more interested in the RSPB than the PSBR, studying Bill Oddie while his more ambitious colleagues pored over John Maynard Keynes.

When Alice Thomson and I interviewed him in November, he insisted that he had no ambition to return to frontline politics unless the Tories got back into power. “I prefer to be a backbencher. It's tedious being an opposition spokesman, you have to do one subject, you are bound by collective responsibility, you can't suddenly say sorry I'm not here next week, I'm in a rainforest,” he said.

Yesterday, however, Mr Clarke decided to exchange his binoculars for the prospect of a red box. After three Tory leaders who did not seem much more appealing to him than Tony Blair, he actually wants Mr Cameron to beat Gordon Brown. “It really matters that the Conservative Party wins the next election,” he said. Announced on the day that the Government set out its plans for a second multibillion-pound bank bailout, his appointment could help to seal a Tory victory on polling day.

Mr Clarke is the perfect foil to Mr Cameron. His experience as the Chancellor who steered Britain out of the last recession undermines the Prime Minister's accusation that the Tory leader is a novice who cannot be trusted to deal with the economic crisis. Although Labour will flag up his support for a cut in VAT, he made clear at the time that it should only be introduced if it was affordable. His suggestion that the Tories would be “asking for trouble” if they promised tax cuts at the next election in fact reinforces the position adopted by George Osborne, the Shadow Chancellor, against complaints from the Tory Right.

There is a cultural benefit to the appointment too. Mr Clarke's man-of-the people reputation will balance Mr Cameron's image as a Tory toff. One of the most off-putting aspects of the Tory leader's circle is the sense that it is an elitist West London clique. The new Shadow Business Secretary belongs to Ronnie Scott's rather than the Bullingdon Club, he wears Hush Puppies not plus fours and is more likely to be found staying at a grungy B&B than on a Russian oligarch's yacht. He wouldn't be seen dead at a dinner party in Notting Hill.

Despite his strong views on Europe, Mr Clarke comes across as a moderate. With his stomach, his cigars and his white removal van, he is reassuringly unflashy, ungreen and un-PC. In focus groups, he is one of the few MPs that voters recognise. People love him because they think he is authentic. Like Boris Johnson, he is a politician who somehow captures the anti-politics mood.

There is a risk, of course - the very willingness to speak his mind that makes Mr Clarke appeal to the electorate makes him dangerous to party managers. He has an arrogance that will make him hard to control - there is no chance of him following the “line to take” issued daily to all frontbenchers from Tory high command. Like Lord Mandelson, whom he will shadow, he has nothing to lose. He does not feel in awe of a leader he once sacked as a special adviser at the Treasury.

Moreover, a party that tore itself apart over Europe for more than a decade once again has a fissure over the issue at the very top. William Hague is among the senior Tories who have always been implacably opposed to Mr Clarke - he voted for Iain Duncan Smith to become Tory leader (ensuring his victory) because he did not believe the alternative candidate, Michael Portillo, could beat the pro-European former Chancellor in a poll of party members. It is presumably no coincidence that Mr Cameron anointed Mr Hague as his deputy days before announcing the return of Mr Clarke - a way of keeping the Shadow Foreign Secretary and his fellow Eurosceptics sweet.

Although Mr Clarke has promised not to rock the boat over Europe, he will find it difficult to keep his views to himself should the Irish vote in favour of the Lisbon treaty this year, or the Tories pull out of the European People's Party in the European Parliament. In our interview he said that he did not think it was the right time to join the euro but called for the creation of a unified European regulatory system for banks after the credit crunch. “Europe has got to come closer together,” he said.

In the end, however, the next election will not be about Europe. By appointing Mr Clarke to his front bench, Mr Cameron has shown that he is more interested in winning power in Britain than in redrawing party allegiances in Brussels. By supporting a move that could be seen as undermining his own position, Mr Osborne has demonstrated that he cares more about his party's electoral prospects than personal ambition. The question now is whether Conservative rightwingers will accept the promotion of a man whom they see as the enemy of everything they believe in.

For more than a decade some in the Tory Party have considered ideological purity - particularly over Europe - more important than winning power. They chose their leaders on the basis of their Euroscepticism rather than their electability, they fought campaigns to save the pound when the voters were interested in saving their schools.

With the appointment of Mr Clarke, Mr Cameron has shown a ruthless commitment to electoral success rather than political ideology. But does his party still prefer the purity of opposition to the compromises required by power?

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