Actor Charlie Hunnam studied UFC tough guy Conor Mcgregor to perfect his scrappy King Arthur character.

The Sons of Anarchy star plays the mythical king in director Guy Ritchie's new movie King Arthur: Legend of the Sword, and Hunnam admits he wanted to make sure he looked like a fighter onscreen, so he watched endless McGregor footage and channeled the Irishman during battle scenes.

"We spent a lot of time looking at people out there in the world doing that (fighting)," Charlie tells Entertainment Weekly. "Particularly Conor McGregor was somebody that I drew a lot of inspiration from and that Guy and I discussed a lot.

"I saw one interview with him... and he was talking to a journalist and the journalist asked what specific challenges that he thought (his opponent) would pose to McGregor, and he said, 'There is no opponent. I'm in the octagon by myself. It’s only me and my own fears and the execution of my own ability that is going to win or lose a fight for me'.

"It's all about self-belief and knowing what you're capable of. And if you're dialed in and focused to your true potential, then any obstacle is going to crumble before you."

Hunnam, who passed on playing Christian Grey in the Fifty Shades of Grey movies, insists King Arthur is a role he was born to play.

Speaking at the film's London premiere on Wednesday (10May17), the actor confessed he was obsessed by John Boorman’s Excalibur movie as a child - and the 1981 film made him want to become an actor.

"I spent most of my childhood messing around with swords and pretending to be either a knight or a wizard, so I had a lot of practice pretending to play King Arthur before actually being hired to do it professionally," he said.