Just as Lord Heseltine emerged from obscurity last week to commend Ken Clarke to us as “a professional bruiser” who is “capable of landing punches on this government”, it transpired that the heavyweight Tory leadership contender had sustained a broken nose. But, as far as we know, he suffered the fracture not while pummelling his political enemies but during a bird-watching holiday in Germany. This reminder that Ken is a devoted twitcher underlines that he is a complicated man of contrasts, more clearly so than any of his leadership rivals.

Heseltine described Clarke as “head and shoulders ahead of any other candidate”. In terms of experience, at least, that is true. He has served longer in high office than any member of the present government. Having been both home secretary and chancellor of the exchequer trumps even Sir Malcolm Rifkind’s record as defence and then foreign secretary.

It also means that Clarke is more familiar to his colleagues than the other candidates. That is not an advantage. John Major, William Hague and Iain Duncan Smith were all elected because they were the least known contender and so had attracted the least hostility.

The Tories have rejected Clarke twice already because he favours European integration. Like Ted Heath and Roy Jenkins, it has been a passionately held view of his since university days. As prime minister he would want to take Britain into the euro if the opportunity occurred. His recent expression of disappointment at the failure of the currency to bring greater prosperity is mere mood music that does not signal any change in his views.

The man the Tories will shortly elect as leader will not enter Downing Street. The party’s recent electoral performance was too dismal to offer any hope of returning to government next time (especially given that the electoral system helps Labour more than the Tories to translate votes into seats).

So Tory MPs, who will have a free hand in choosing the leader if the changes to the party’s constitution are agreed next month, do not need to worry about whether as prime minister Clarke would march them into the single currency. As leader of the opposition he could do little damage because, during this parliament, there will be no referendum on the euro, nor on the European constitution, after the “no” votes in France and Holland. It would not be hazardous for the Tories at this moment to elect a Euro-enthusiast. After the 2009 election Clarke, 65 already, would have to step down.

The party should be in no doubt, however, that Clarke is ruthless. As chancellor he used masterfully the leverage that came from being indispensable to the government. He nearly always got his way, to an extent that only Gordon Brown has surpassed in modern British political history.

Thanks to Clarke’s steadfastness (or obduracy) the Tories were unable to pledge that Britain would not enter the euro during the 1997-2001 parliament (a debate that now looks absurdly irrelevant). He stoutly resisted any commitment to hold a referendum on the subject, fearing that public opinion might veto what the government wished to do. It was his idea to punish Tory MPs who rebelled on European bills by taking away the party whip, which was “brave” since the government had almost no majority.

That steeliness is not an argument against electing Clarke. The party needs to be controlled. David Davis, although a tough-looking guy, has never had to demonstrate such skills and yet is not popular with those who have worked for him. Clarke remains likeable even to people like me who have received a bruising from him.

We do not know in which direction Clarke would lead the party. He is not much interested in so-called modernisation and you would not call him a social liberal. That is disappointing to me, but the point of modernisation is to put the party back in touch. Clarke effortlessly gives the appearance of being in touch because he behaves so naturally.

Despite being a leading member of the despised Conservative administrations of the 1980s and 1990s, Clarke is not seen as other Tories are. People do not regard him as a toff. They do not assume that he is hostile to the National Health Service or indifferent to public transport and state schools. Having had cabinet-level responsibility for both health and education, he speaks easily on those subjects, in contrast to the party’s leaders since 1997.

A drawback is that Clarke gives an impression of having arrived at his views on any issue years ago and of being reluctant to revise them. When in 1976 Harold Wilson resigned as prime minister, he said he feared that since he was now seeing issues that were coming round for a second time he would not approach them with fresh thinking. Clarke needs to reflect on Wilson’s point.

Another problem is that Clarke talks too much. In any bilateral conversation with him it is a struggle to get a point in between his torrents of good-humoured speech. It reinforces an impression that his mind is made up and that he has difficulty listening.

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