Angela Merkel, the German Chancellor, was in celebratory mood yesterday despite the growing tensions in her coalition Government. The reason: her notoriously grumpy husband is drawing glowing reviews for his international debut as First Spouse.

Joachim Sauer, 57, a dour research scientist, used to be known as the Phantom of the Opera because he was only ever sighted at his wife’s side during Wagner performances. Even then he appeared often to be suffering from a migraine.

At the weekend EU summit, however, he seemed to become a charismatic figure who could help to transform Ms Merkel’s position on the world stage.

Professor Sauer’s particular admirers, according to the Merkel-watcher Hugo Müller-Vogg, were Bernadette Chirac, Cherie Blair (who gave him a peck on the cheek) and Maria Kaczynska, wife of the Polish President. Gerd Langguth, Ms Merkel’s biographer, believes that the professor’s priority is to avoid looking like a buffoon. “Sauer is doing everything so as not to fall into the mould of Dennis Thatcher, the much-mocked husband of the Iron Lady,” he said.

It is not altogether clear what the professor has done to change his image so radically. He delivered a toast to Europe, showed the first wives the Brandenburg Gate — and laughed a lot. That apparently was the breakthrough. Professor Sauer has not previously been photographed with a smile on his face.

One of the best quantum chemists in Europe, he does not suffer fools gladly. Nor does he like journalists (“I will answer questions only on my research, not on my wife’s work”). And he hates noise. When his grown-up sons come to visit, they have to wear thick woollen socks.

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