You'd have to shell out €325 to replicate Kate Middleton's exact look on this occasion.

It's not the first time an item of clothing worn by the Duchess of Cambridge has sold out but this is definitely one of her more casual ensembles. Kate, joined by husband Prince William and brother-in-law Prince Harry, took on the challenge of a sprint race at London's Olympic Park yesterday. They're heavily involved with the Heads Together, a mental health organisation which has partnered with the London Marathon this year, and the trio headed down to support runners who were gathered for some training. Prince Harry claimed first place and Prince William just about edged past his wife to make second, but aside from the fun had at the event, people were also very interested in Kate's laid-back outfit. The jacket is from Perfect Moment and retails at £280, working out to about €325. To give it its full description, this is the Mini Duvet Quilted Ski Down jacket and it's currently sold out on Net-a-Porter, proving that Kate's style is as popular as ever. The mother-of-two teamed it with jeans and New Balance runners and to be fair, her off-duty fashion sense is just as impeccable as her usual elegant look.