Olympic silver medallist Zara Phillips raises fashion bar in Stella McCartney

Proving once again that London 2012 is turning out to be a fashion triumph is Zara Phillips, whose elegance in equestrian kit is a lesson in the power of clothes. The fashion bar is high in this particular sport – Hermès designed the blazers for the French team – but Stella McCartney has done a beautiful job. The sense of occasion that makes equestrian chic such a perennially good look has been retained, embodied by the tailcoat detailing, the double breasted jackets, the gleaming buttons and creamy cravats – but the lines have been sharpened with a modernist's eye. A keen horsewoman herself, McCartney was well placed to understand what works. Dressed like this, Phillips is revealed as a beauty. A discreet but professional-looking make-up job and a Kate-Moss-off-duty bun highlight those world-class cheekbones. The navy, white and red combination suits her, whether she is in jodhpurs or a warm-up tracksuit top and shorts. Off-duty, the Queen's granddaughter seems trapped between two looks, neither of which suit her. Her downtime get-up of rugby shirt and mirrored sunglasses is slightly Wetherspoons-Saturday-night. Her dressed-up look of fussy fascinators and shiny dresses winds up looking like a caricature of femininity. The riding gear is a neat middle ground that allows Phillips to look like the alpha female she is, rather than a woman boxed into the mould of a tomboy or a Sloane wife. The power of a flattering pair of trousers and a well-tailored jacket has been a hot catwalk topic since Phoebe Philo, a British designer who spent the early part of her career as McCartney's righthand woman, relaunched the French label Céline with an aesthetic of clean, androgynous lines and bold, graphic colour combinations.