14/08/2014 16:43 BST | Updated 20/05/2015 10:12 BST

Emma Watson Is Stunning In White Shirt And Floor-Sweeping Skirt For Prince William's Party At Windsor Castle

It's one thing dressing for the red carpet but what does a girl wear when she's invited to a party thrown by Prince William at Windsor Castle?

Emma Watson made a good case for wearing a plain white shirt as she arrived at the event to celebrate the work of the Royal Marsden Hospital.

The Duke Of Cambridge Celebrates The Royal Marsden

The actress was joined by some of the biggest names in film and fashion, from Kate Moss and Cara Delevingne to Margot Robbie and Cate Blanchett.

Many of the guests, including Emma, were dressed in pieces by designer Ralph Lauren, who is funding a breast cancer centre at the hospital.

She tucked her shirt into a floor-sweeping grey skirt which she accessorised with a matching box clutch and silver necklace.

The best part of Emma's look? It had to be her berry-red lipstick and her swept-back updo.

The Duke Of Cambridge Celebrates The Royal Marsden

The guests enjoyed champagne and chatted to the prince in the castle's Waterloo Chamber. Wouldn't you just love to know what was being said in this conversation above?

Kate Moss also looked stunning in this black and sheer dress paired with sandals and drop diamond earrings.

The Duke Of Cambridge Celebrates The Royal Marsden

As for one of our favourite looks of the night? It came from Cate Blanchett, who looked incredible in this all-white gown. (We reckon this photo is one for the mantle piece...)


Love these ladies' looks? See who else joined Emma, Kate and Cate at the party in the gallery below and no, unfortunately Duchess Kate doesn't make an appearance...