Prudence is a shoe-in for Mrs O

In a nod to her host's most abiding character trait, she wore the same green leather Jimmy Choo court shoes the world first saw in January, on her husband's inauguration day.

For why waste money on a new pair of shoes when an old pair will do? With the price of a pair of Choos at around £350, Mr Brown will no doubt approve of Mrs Obama extracting her full money's worth.

Perhaps he will even urge her to wear them for a third time, so their average cost-per-wear becomes a less profligate £116.66. Even so, he is likely to breathe a sigh of relief that his own wife's tastes do not extend to such luxuries.

At the Royal Opera House this morning, Mrs Obama scored another hole in one, albeit in a rather literal sense.

Was she dressed for the theatre, or the golf course? One explanation for her bold Argyle print cardigan was that it paid tribute to her hostess's Scottish roots, in a reciprocal move to Sarah Brown's choice of an American-born British designer, Britt Lintner, yesterday.

But the cardigan bore all the hallmarks of her style, embellished as it was with just a flash of turquoise sequins to elevate it above the average, humdrum cardie. Whether she was tee'd off that Mrs Brown had also chosen a blue suit, we will never know. Sometimes, fashion clashes are just par for the course.

At last night's Downing Street reception, meanwhile, the gloves were off - and the arms were out. Slipping off her calf-length opera coat, a black duchesse satin affair by one of her favourite designers, Jason Wu, she revealed a chic black and white sleeveless dress.

The dress, a crepe silk "tuxedo-tank" with a bow belt by Isabel Toledo, was a wise choice, both for dinner and to meet the Queen. Mrs Obama looked thoughtful and formal. But she couldn't quite banish that signature playful element, as evidenced by the frothy tulle underskirt that created a jaunty swing.