The actress, who plays Brienne of Tarth on the cult fantasy series, announced the news in a statement on Monday (20Jul15), revealing she's a longtime fan of the colourful fashion queen.

She says, "I am so proud to be part of Vivienne Westwood's A/W 15 campaign. I have admired Vivienne ever since I can remember for her revolutionary mind and exquisitely rebellious design.

"I love the unisex theme of this collection. It is so relevant for Vivienne Westwood to reassert their activist mindset and create a collection that takes us beyond our current gender stereotypes with beauty and intelligence."

Westwood adds, "At the time we were planning our next Gold Label AW15/16 show... I realised Gwendoline would be perfect and would fit the clothes, so I asked her to do it. She is such an attractive woman. When I asked her to be in the show, as well as the campaign, we got to know each other, she is a really interesting woman."