Sarah Sands: The assassin who feigns innocence rises to the top

In June, I published in the Reader's Digest an interview with David Miliband, in which he spoke tenderly of his adopted sons and passionately about improving the lot of mankind. In other words, it was an op-portunistic bit of political positioning. Last week, the Foreign Secretary wrote a high-falutin piece for The Guardian about his vision for the Labour Party. Backbenchers demanded his resignation for this disgraceful attempt to oust Gordon Brown.

What Miliband would like is to be called into service by his party, like an honest soldier, even if he has only a Napoleonic hundred days of glory before the Battle of Waterloo. This is not about personal ambition, but desperate times. Miliband surely proved he was not ambitious last year, by putting the adoption of his son above a leadership contest.

In Robert Harris's Roman novel, Imperium, a study in political ambition, Cicero remarks dryly: "Always beware of the man who says he is not seeking office for himself, for he is the vainest of the lot." It might be refreshing to hear a politician say he is running for office for the thrill of personal power, but it would not do him much good. The late Tory minister Alan Clark was candid about the aphrodisiac of power and access, and was continually excluded.

David Davis was uncomplicated about his ambition during his leadership contest with David Cameron, but for all his plotting and intrigue he was beaten at the political game by Cameron's aura of a higher political destiny. This may explain why Davis ended up sacrificing himself pointlessly for a lofty cause of civil liberties. The moral high ground in politics is of such soaring altitude that it is surprising anyone can breathe.

The entirely high-minded do not, of course, stand a chance. They would not be there in the first place. Robert Harris, who has made a lifetime's study of the subject, remarked to me that normal people do not tend to pursue politics. Why would you? Yet politicians have to perfect the artifice of normality. This was Blair's gift, and not Brown's. They also have to combine incredible cunning and ruthlessness with a sincerely held sense of innocence.

Any charges brought against them are greeted with wounded bafflement. Brown is in a permanent state of bewilderment, whether because of Cherie Blair's book, or David Miliband's disloyalty. Barack Obama combines astonishing political efficiency and realism with saintliness. New Yorker cartoons and McCain's jibes are treated with heavenly distaste. I rather miss Hillary Clinton's blue-collar version of ambition – dirty and authentic.

In all professional fields, people make the mistake of declaring that ambition is a virtue. Any graduate CV will talk of being ambitious. But the higher you go, the more opaque it needs to be. You need to appear calm and humble, while secretly clutching a thousand snake-like strategies to your breast.

I once watched a formidable journalist almost lose the top prize of an editorship. His mistake was to let his record speak for itself while a rival lobbied the proprietor brilliantly, and almost swung it. Entitlement is dull. Everyone likes unexpected, even undeserving, winners.

At work, people are put off by open ambition. It looks ugly and presumptuous. Yet there is no such thing as an effortless rise to the top. The most talented or qualified people are not necessarily the most successful. Indeed, the writer and teacher of ethics, Alexander McCall Smith, once told me he wrestled with the question of whether it was possible to be virtuous and very successful. If Miliband wants to be Prime Minister he has to master the sublime hypocrisy of being the innocent assassin.

Sarah Sands is editor in chief of British 'Reader's Digest'