How does Barack Obama do it? Does he stay up all night learning his lines and then practising them in front of his bedroom mirror? That can’t be the case, and yet, somehow, he manages to remain clear, sharp, fluent, more or less flawless in his diction.

Flawless in appearance, too. There was a banner that read: “Vote B.O.” That was a bit misjudged. There can’t be a politician who looks and acts more clean-living: that white shirt, that dark suit, that blue tie, that slight but friendly frown, that big smile as he said “thank you” a total of, by my count, 12 times. His look is so crisp and precise there is nothing to detract from the power of his oratory.

Hard to say which moment was the most eloquent in a speech that touched on so much: his own humble origins, the Berlin airlift, reconciliation in South Africa and Belfast, the perils of nuclear proliferation, the differences between America and Europe, and the walls that have fallen in Germany and must fall elsewhere. Mr Obama talked a lot about bringing down walls, and made that sound more than the political cliché it is.

So what’s his basic strength as a speaker and, perhaps, an actor? Well, he has obvious qualities that many thespians might envy. He exudes a confidence that never teeters over into arrogance and grandstanding. He does not wave his hands about very much, and when he does it is not an empty gesture but serves to underline a point. He knows when and how to be still. He resists going over the top — any great actor delivering a key speech in Hamlet or Macbeth knows to favour such restraint.

And there is much more to him. He can sound high-minded yet rooted, idealistic yet grounded, exhilarated yet calm, warmly American and yet a bit of a European too. And, yes, presidential — it is there in his confidence and in his willingness to think and talk big with measured inspiration and an attractive humility. He didn’t go so far as to say “Ich bin ein Berliner”, like John F. Kennedy all those years ago, but to judge by the excitement with which they greeted him, the Berliners clearly thought that he was that — and more.

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