Doctor Who cast banned GoT spoilers
The Doctor Who cast banned Game of Thrones spoilers on set when actress Maisie Williams guest starred.
Williams, who plays Arya Stark in Game of Thrones, is due to star in an episode of Doctor Who.
Peter Capaldi, who plays the Doctor, said: "We had to make sure she didn't give us any GoT spoilers, we didn't want to know anything at all."
So far no details of Williams' Doctor Who character have been revealed, but Jenna Coleman, who plays Clara, said: "I don't think we're allowed to give anything away, other than to say she is utterly brilliant as you would expect, and it's a very surprising and intriguing storyline with her connection to us and her connection to the Doctor."
Capaldi described her upcoming stint on the show as "cosmic".
"I love cosmic, it's such a great word, it covers so many bases," he said. "She's wonderful in it, and also, what's great about Maisie, she changes, she metamorphosises.She's metamorphic.
"She's so different, without giving anything away, the way she acts, the different aspects of her character, is very exciting and compelling and very impressive for someone who is so young."
When asked which other stars the cast would like to see make guest appearances, Michelle Gomez, who plays Missy aka The Master, volunteered the Queen and singer Tom Jones.
Coleman said she'd love to have Helena Bonham-Carter star in the show, and Javier Bardem because "he'd be a good villain".
The ninth series of Doctor Who is set to air on BBC One this Autumn.