Guy Ritchie picked Charlie Hunnam for the lead role in 'King Arthur: Legend of the Sword' because of his "enthusiasm".

Guy Ritchie and his wife Jacqui Ainsley

Guy Ritchie and his wife Jacqui Ainsley

The 48-year-old director is at the helm for the upcoming fantasy movie, and has said he knew he would give Charlie the role as the titular monarch as soon as he saw his screen test, because of the passion he put in to securing the role.

Speaking exclusively to BANG! Showbiz at the London premiere of the movie in Leicester Square on Wednesday (10.05.17), Guy said: "Charlie was enthusiastic to get the role and seeing that enthusiasm I knew I wanted him. I hadn't made up my mind but when seeing his screen test he was perfect for the role and you know what he is a really nice guy as well."

And Charlie, 37, also sung Guy's praises as he branded the filmmaker as "absolutely sensational" to work with, as his "primary direction" was always to make sure the cast had "fun" on set.

Charlie said at the premiere: "Guy is absolutely sensational working with but he is bad about doing any preparation. I was very nervous about things and wanted to talk about it but he just said we will do it later. But the best advice he gave was he said we need to have fun. If we have fun, we will make a good film. If the primary direction from the director is to have fun, it's fantastic."

'King Arthur: Legend of the Sword' also stars Jude Law as King Vortigern, Eric Bana as Arthur's father Uther Pendragon, and 'Game of Thrones' star Aidan Gillen as Goosefat Bill. Retired soccer star David Beckham also makes a cameo in the feature.

The movie is due to hit American theatres on Friday (12.05.17), and UK cinema screens on May 19.