Kate Middleton at the Day-Glo Charity Roller Disco at the Renaissance Rooms, Vauxhall, London, UK.

Kate Middleton at the Day-Glo Charity Roller Disco at the Renaissance Rooms, Vauxhall, London, UK.

Kate Middleton's blue dress she chose for her engagement photocall instantly sold out.

Kate, 28, chose the Issa London sapphire dress to officially announce her engagement to British Prince William.

She wore the dress as she appeared with her husband-to-be at St James' Palace as they posed for photographers.

Kate showed off her engagement ring, which once belonged to William's mother Princess Diana.

According to Marie Claire, the £385 dress sold out instantly on the Matches website.

Her choice of engagement dress has now sparked rumours that she will choose the designer, who has recently started to create custom-made bridal dresses, for her wedding gown.