Ritchie's version of the oft-told tale sees Hunnam's Arthur raised in a medieval brothel with no knowledge of his royal bloodline after the murder of his monarch father.
Arthur works as a gangster on the streets of Londinium until he one day pulls a magical sword from a stone and is forced to face his destiny.
Gillen plays Goosefat Bill, a new friend who tries to help Arthur on his quest.
Asked by UPI in a recent phone interview what he initially thought upon hearing Ritchie -- the "Snatch and Lock," "Stock" and "Two Smoking Barrels" filmmaker -- wanted to tackle Arthurian lore, Gillen said he thought the match of man and material made perfect sense.
"I wasn't that surprised, actually," the 49-year-old, Irish actor recalled.
"I may have been, if I hadn't had seen the Sherlock Holmes films [2009's 'Sherlock Holmes' and 2011's 'Sherlock Holmes: A Game of Shadows.'] But having seen the 'Sherlock Holmes' films and clocking what he had done there with taking a well-known or well-loved tale or series of tales and making it into something peppy and funny and fast and a kind of irreverent take on it," he explained.
"Although it's not irreverent, yeah, because those stories are entertainment for the masses. So, I thought he did a pretty great job, actually, of re-invigorating it. So, I didn't think it was that unusual and particularly undoable. I thought he'd do a good job. ... Taking an age-old, English myth and making it feel contemporary, if you like, or putting a contemporary energy into the way it is filmed and the way it is acted and the way it is edited. How it looks, how it sounds."
"And putting that kind of male camaraderie -- not that it's exclusively male -- but it's what he does. The central relationships in his films tend to be about guys more than they are about women or about gangs. And a take on this with Arthur being a street kid or an urchin, coming up from the streets, is pretty him and I think it works."
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