Game of Thrones star Daniel Portman on stage at Sheffield Crucible in The Last King of Scotland

Daniel, who played Podrick Payne in the epic TV fantasy series, stars on stage at the Crucible, Sheffield in a stage adaptation of the Giles Foden novel, mixing fact and fiction about the bloody eight-year rule of 1970s Ugandan dictator Idi Amin Dada.

The 2008 film of the book starred Forest Whitaker and James McAvoy.

Daniel plays Scotsman Nicholas Garrigan, the personal physician to Amin who becomes his confidant.

The British secret service try to involve him in a plot to overthrow the president when Amin decides to expel Asian people from the country and they realise they have lost any control over him.

Daniel said he had steered away from watching the film again. “The great thing about this is the film is the film and the book is the book and the play is the play. They are variations on the same story told differently.”

He felt that Nicholas in the play is far more complicit in what’s happening than in the film version.

“The film has more of a simplistic outlook with ‘good guy, bad guy’. In this there’s a more grey area where actions speak louder than words.”

He added: “It's a very complex journey for Nicholas. I believe he is very opportunistic in a good way and a bad way.

“He’s gregarious, flirty and fun but with that comes the ability to manipulate. If you're used to people liking you and getting on with you, you have an understanding of how you can influence people’s behaviour towards you.”

He is interested in how his character views the brutality that took place in Uganda: “I definitely feel Garrigan is guilty of wilful ignorance in terms of what’s going on.

“He’s almost looking at the world as a painting, as a TV show, not what’s outside the window, instead of really taking in what’s going on.”

Daniel said that Garrigan is far more interested in extending his influence at the heart of the regime.

In trying to figure out his character’s motivations, he’s faced difficult questions. “I don’t know how I would react in that situation. I’d like to think for the greater good.

“He’s caught between such a dangerous rock and such a dangerous hard place. It’s big challenge for me and one of the great joys of this jobs has been the whys.

“What makes him tick is a big part of that.”

Daniel praised his fellow cast members in their journey of discovery about the play, which has its world premiere in Sheffield.

“I think we’ve been very lucky in the fact that it’s a warmth in the (rehearsal) room and a really good group of people that are willing to be open and trust each other.

“There seems to be a distinct lack of ego in the room which is very useful when you’re doing such an ensemble piece.”

Daniel, aged 27, is used to ensemble work after seven years on Game of Thrones. He said: “It was great. It’s done. I loved it and made a lot of great friends.

“I had a lovely experience on it and it’s given me a lovely profile.

“I have a lot of work to do as an actor if I hope to be the actor I hope I can be. That’s where we are now. I have choices and try to do work that asks different kinds of questions.”

The Last King of Scotland runs at the Crucible from September 27 to October 19.