Feeling comfortable in one's clothes speaks volumes, as the appearance of Samantha Cameron and Michelle Obama out and about during the visit went to prove.
Despite the fact the American First Lady's attire was quite frilly – the mustard and lace L'Wren Scott cardigan she wore is not minimal – and her trousers were wide-legged and therefore going against the mainstream, she still looked as if she'd thrown on her outfit and gone out without a second thought.
Mrs Cameron was trying harder. Not content with wearing a "new season" colour – her top was designed by Roksanda Ilincic, incidentally – she belted it. What for, one might not unreasonably ask? It would have looked neater and simpler without this entirely cosmetic detail, the point of which was presumably that it matched her navy, peg-legged, cropped Joseph trousers and navy suede shoes.
A look has rarely been so studiously co-ordinated since the 1950s, or so gratuitously accessorised since the 1980s.
Much has been made of Mrs Cameron's position as an ambassador for the British Fashion Council, and she certainly wears British designers' clothing on many occasions. But, her style in this instance is self-conscious. Mrs Obama, however, appears to have more important things to worry about than fashion, and looks all the more fashionable for that.