Kate, Emma, Margot: Prince William's sexy, stylish guests

Celebs join the Prince to celebrate the work of The Royal Marsden Hospital, of which he is president.

Fashion designer Ralph Lauren announced that he'd be funding a new breast cancer centre at the hospital.

William's wife, Catherine, the Duchess of Cambridge, was conspicuous by her absence.

But here's who showed up:

Supermodel Kate Moss looked stunning as always in a black slinky dress with a thigh-high slit and a boxy clutch.

Moss' rockstar husband Jamie Hince cleaned up pretty well too and looked dapper, not to mention particularly youthful.

Kate Moss' younger counterpart and newly single Cara Delevingne looked just as breathtaking as she turned up for the ball without her girlfriend Michelle Rodriguez.

Margot Robbie, the newest star in Hollywood also turned up looking particularly dishy in a metallic grey number.

Then of course there was Cate Blanchett who nailed it in white...

And model Jessica Michibata who seemed like the only one in the crowd in a racy red gown... not that we're complaining :-)

Could any celebrity gathering in Britain ever be complete without Emma Watson these days?

The British actress was as elegant as they come in this stylish white-and-grey number.

On your extreme right is designer Ralph Lauren, who has promised to fund the breast cancer centre at the hospital with his wife of 50 years, Ricky Anne Loew-Beer and Prince William.

The entire Lauren clan poses for the shutterbugs.

Designer Ralph Lauren has been a vocal supporter on the campaign against cancer for over 20 years.

He's lost his friend Nina Hyde, the Washington Post fashion editor to breast cancer in 1990 and has donated millions over the years.

Like many guests, Helena Bonham Carter too was clad in a Ralph Lauren creation and confessed to have been tad drunk and asked Prince William to be her child's godfather :-)

Arguably the most stylish man in Great Britain, Benedict Cumberbatch also turned up in a Ralph Lauren Black Label Peak-Lapel Tuxedo and Dress Shirt.

Cumberbatch is seen here with the Laurens.

Holding her own: Emma Watson seems keenly interested in listening to what the Prince has to say as Kate Moss looks on.

And we wind up with the young and upcoming actress Lily James who stars in the immensely popular British period drama, Downton Abbey.