It's not often that the younger members of the royal family are all seen out together. But today's rare gathering of the Queen's extended family for a celebration of her 90th birthday at St Paul's cathedral naturally meant the style stakes were high. All eyes are usually on the Duchess of Cambridge, but with Princesses Beatrice and Eugenie, Zara Tindall and the intriguing Lady Amelia Windsor in attendance she had some stiff competition.