If there was a competition for best dressed dignitary, then it was a dead heat. Sticking to her own trusted dressmaker, the Queen wore a Kelly and Pordum cream coat, and hat by Angela Kelly.

But it was Carla Bruni Sarkozy who demonstrated the greatest transformation, abandoning her usual hippy-infused style for a vintage look that was part Jackie O, part district nurse.

Mrs Sarkozy also showed an unlikely taste in handbags, sporting a vintage number that was striking in its similarity to the classic style that has become the Queen’s signature accessory. The former model took no chances by wearing Dior top-to-toe. Her entire outfit, from the 1960s pillbox hat to her grey wool coat and black leather gloves, was designed by the French couture house – a diplomatic choice, given that it is headed by the English designer, John Galliano.

Dolly Jones, editor of Vogue.com, said: “With all eyes on her today – some of which are inevitably going to look for any excuse to be critical - Carla Bruni was perfectly demure, her tiny matching hat and rounded collar an elegant reference to Jackie O.

“Without trying too hard to make a statement, she really looks the part, while the sober grey wool fabric of her coat dress blends into the British weather. She’s certainly not trying to upstage anybody – that seems to be the message.”

Lucy Yeomans, Editor of Harper’s Bazaar, said: “It was very elegant, but very, very safe, with all the accessories, like the gloves. My first impression was that it was kind of Jackie Kennedy meets Madeleine, the little French schoolgirl. I also thought it was eerily reminiscent of the young Lady Diana when she was trying to do everything correctly.”

She added: “It was very beautifully tailored and in its way, very on trend, but it was also a little bit nun-like. I don’t know whether it was because she knows that there is this naked picture of her around.”

Later there were more admiring glances for Mrs Sarkozy when she was placed between the Duke of Edinburgh and the Prince of Wales and three seats from Gordon Brown at the evening banquet at Windsor Castle.

At a table 182ft long, 148 guests sat down to a state banquet in honour of the French President, who sat between the Queen and the Duchess of Cornwall. In the far distance other guests included David Cameron, the Tory leader, and Nick Clegg, the Liberal Democrat leader, attending his first state banquet. Dame Ellen MacArthur, the yachtswoman, and Andrew Marr, the broadcaster, sat a long way from the presidential guests while Michel Roux, one of England’s best-known French chefs, was placed well below the salt.

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