Matt Smith found it "difficult" filming 'House of the Dragon' without Emma D'Arcy

Matt told Variety: "It was difficult to do it without them because I love them - a person of real depth and sardonic humour and fierce intellect."

Emma added: "It was kind of rubbish! The man has incredibly high standards, so you at least have a chance of the work being satisfying. I have petitioned for more time next season."

But Matt did get to share a number of scenes with award-winning stage star Simon Russell Beale, who will play Ser Simon Strong, the guardian of Harrenhal, and they had "a hoot".

He said: "We used to just have a hoot!

"He'd say, 'Oh, darling, I'm bored of this acting. Come in here for some light chitchat.' Amazing brain!"

Matt is unsure if the "sporadic, intense points of connection" that make for on-set relationships are particularly "healthy".

He mused: "You're all working tirelessly to create something and that is intoxicating. But ultimately, is that a healthy thing? I don't know. Not according to therapy."

The former 'Crown' actor admitted he needs to find more "balance" in his life when he's working.

He said: "I'm quite dedicated when I work, and it becomes a solitary experience. I probably need more balance.

"I get tunnel vision - I don't think I make enough room for a life."

The British actor is still close to his former 'Doctor Who' co-star Karen Gillan.

He said: "I'm so proud of her. She always had her eyes on the prize - she knew she wanted to move to L.A. and make big films, and she f****** did it."