Laura Bush looks exactly as you would expect a woman who has spent the past eight years in the White House to look. Polished to perfection, her brown dress conservatively tailored in the approved manner, her stance composed and slightly regal, her smile unwavering. She may be suppressing a desire to stick two fingers up at the press, but you would never know it.

She has endured too long to fall at the last hurdle. With good behaviour, she’ll be out in a few weeks, and nothing is going to crack her composure.

By contrast, Michelle Obama cuts a more spontaneous figure. Like her husband, she is leaning keenly towards the onlooker, smiling more as though she were posing for a holiday snap than for the world’s press. Her expression is a mixture of mild impatience and bemusement. But what really stands out is her red dress, a garment that betrays her excitement in more ways than one. The colour is racy, the cut (empire-line with a pencil skirt) emphatically sexy. And it has been a long while since a neckline as fashion-forward as this has been spotted within a mile of the Oval Office.

It is a dress that requires total self-belief and plenty of chutzpah, not to mention a decent set of curves. It is a results dress: if you wore it on a date, you’d definitely expect a lift home. It’s the equivalent of the Versace safety-pin number that Elizabeth Hurley wore in 1994 to the premiere of Four Weddings and a Funeral. It doesn’t just say, “Look at me”; it says, “Don’t you dare look at anyone else.”

By wearing it Mrs Obama is leaving no room for confusion: she means business. Whether she will still wear scarlet at the end of her husband’s administration remains to be seen. Expect copies in your local Wal-Mart for Christmas.

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