Carola Long: Why the Obama seal of approval really counts

For an up-and-coming designer, publicity doesn't come much better than having Michelle Obama wear your clothes. "First wife" or celebrity endorsement can be a mixed blessing but Mrs Obama's popularity and fashion credentials make her a dream ambassador for any brand, especially a new one.

As well as more established labels such as Azzedine Alaia and the high-street brand J Crew, the first lady has boosted the profile of designers including Jason Wu, who created the full-length, flower-covered dress she wore for the inauguration balls. She's also worn pieces by some of London Fashion Week's emerging names; Erdem and the duo Peter Pilotto.

The success of Michelle Obama's look is down to her ability to look smart and classic, but never fussy and staid, a hard line to tread when dressing for so many formal occasions where playing it safe is preferable to causing an international sartorial incident. Bunmi Koko's "Matriarchy" collection aims to offer a modern twist on conventional power dressing: sharp, understated and without the need to imitate male dress through boxy suits and shoulder-pads.

Mrs Obama favours the clean shapes and bold colours worn by Jackie Kennedy, as well as some of the silhouettes the style icon wore in the Sixties. This coat (above left), by Bunmi Koko, has the kind of simplicity that she likes, but the frock shape adds femininity while the high collar gives it a certain presidential dignity. She also has a penchant for making simple outfits look more individual by adding costume jewellery and this understated design would make the perfect canvas for one of her signature jewelled brooches.