The royal family noted that Miss Middleton had wanted the dress to combine tradition with modernity: its ivory satin gazar bodice narrowed at the waist and padded at the hips to suggest Victorian corsetry, the wide skirt constructed with arches and pleats to evoke the opening of a flower. It was an elaborate design, combining a hand-embroidered floral overlay, a full veil and a train nearly nine feet long.

During the weeks leading to the ceremony, the designer had been under strict instructions not to confirm her involvement. It was only when Ms. Burton, her head buried under a furry trapper hat, was recognized outside the Goring by the belt and shoes she was wearing on Thursday that it seemed likely she was indeed the chosen designer.

Miss Middleton, as depicted in the tabloids and in the Lifetime network’s treatment of her patient romancing of Prince William, is well aware of the image she projects. She has been so careful that she has appeared boring, though that may have been her intention, if she wished to ingratiate herself with a scandal-plagued family.

Almost everything we know about her, in fact, is through her clothing choices. Supposedly, it was at a charity fashion show a decade ago that Miss Middleton, wearing a see-through dress, kindled something of William’s passion. More recently, her sexy-but-simple wraps and suits by Daniella Issa Helayel suggest that she wishes to be seen neither as a decorative object nor as a dominant force. The only real job she has ever held was as an accessories buyer for the London retail chain Jigsaw.

And yet, in her dress choices, she seems more sophisticated about modern life than other royals. It was a controversial, though savvy, decision for her sister and maid of honor, Pippa Middleton, to wear white, also by McQueen. When Pippa picked up the bride’s train, their matching dresses made the sisters appear almost as one entity, distinct from the royals but still part of the family.