Samantha Cameron, the British Prime Minister's wife, did not wear a hat to the royal wedding, instead, opting for a jewelled clasp/barrette in her hair.http://www.dailymail.co.uk/femail/article-1381963/Royal-wedding-ceremony-Samantha-Cameron-VIP-wear-hat.html
I've read several articles, and seen a few things on TV, where many British fashion critics have called her rude, lazy, and that it's a "slap in the face" to the HC to not wear a headpiece.
From the article I posted: "Etiquette guide Debretts reads: 'Hats are traditional, but by no means compulsory, at British weddings, and a matter of personal choice for christenings or funerals."
From Brides magazine: "The accepted rule is that you don't take them off until the Mother of the Bride removes hers. As with most etiquette rules this is based on old tradition; hats were typically removed as the men took off their jackets and retired for cigarettes."
I really don't know much about this tradition or "requirement." Is this a big deal?