Was Burton, the fashion designer tipped to be designing Middleton's wedding dress, the woman pictured arriving at the Goring Hotel?
The woman scuttling into the Goring Hotel, the Middleton family HQ, in London on Thursday hid her long blonde hair under a fur 'trapper' hat in an attempt to avoid being 'spotted' by swarms of photographers and television crews.
The distinctive studded leather belt doubled through the belt loops of her jeans was identical to the one favoured by Sarah Burton, creative director of Alexander McQueen , as were the ballet pumps.
Burton, the Manchester-born designer, who has imbued the radical British brand with a robust femininity and breathtaking feeling of historical romance, is not often photographed. But when she is, the metal belt, buckled, and then individually slotted backwards, and the flat pumps, are present.
The vital accessories seemed to confirm that Ms Burton was on her way to a very special royal appointment indeed.
They appeared to be the final piece of evidence needed to confirm that Ms Burton is indeed designing A dress for Catherine Middleton, if not THE dress itself.
Ever since news was leaked back in March that Ms Burton had been given the royal commission of the century, she has remained the hot favourite to design the dress for the biggest royal wedding in history.
The autumn/winter collection 2011 collection she showed in Paris earlier this year was inspired by "a snow queen and her court" and featured a bevy of white and ivory 'bridal' designs which were triumphs of haute couture craftsmanship.
One dress featured a bodice hand-embroidered in chiffon, tulle and pearls, and a train formed from 500 metres of hand-frayed, hand-pleated chiffon. Another design featured a strapless bodice fashioned from a mosaic of hand-stitched shards of English porcelain.
Ms Burton, from Manchester, joined Alexander McQueen's studio as an intern and rapidly rose to become his 'right-hand', working alongside him on all his collections for 12 years.
Her eye for unique craftsmanship and fabulous modernity is believed to have first attracted Miss Middleton's eye, after Alexander McQueen designed an off-the-shoulder wedding dress for Sara Buys, a fashion journalist who married Tom Parker Bowles, the son of the Duchess of Cornwall, in 2005.
Ms Burton was confirmed as the creative director of Alexander McQueen, part of the Gucci Group, in May, last year. Apart from the spring/summer 2011 and most recent autumn/winter 2011 collections she has shown in Paris, Ms Burton also designed the billowing red-and-black 'poppy' dress Michelle Obama wore for a state dinner for President of China, Hu Jintao, in Washington, last year, and has also created one-off designs for Cate Blanchett, Lady Gaga, and Gwyneth Paltrow.
The choice of Ms Burton has been hailed by the international fashion community and would provide a vital global boost to the British fashion industry.
The swift and suddenly-ended career of Alexander McQueen, who committed suicide in February last year, will be celebrated in the first retrospective of his work, 'Savage Beauty', which opens with the Costume Institute Gala at the Metropolitan Museum of Art, in New York, on Monday night (May 2nd). The event is being chaired by Anna Wintour, the editor-in-chief of American Vogue; the Oscar-winning actor, Colin Firth; and the British designer, Stella McCartney, whose label is also part of the Gucci Group.