Dominic West, who plays the charismatic leader of the Ninth legion, General Virilus, was an important contributor to the energy of the production – both on and off screen.

Neil Marshall: "Dominic brings a real kind of brash energy to the role. I'm sure the spirit of Oliver Reed possessed him. Certainly, during his opening sequence where he's drinking ale in a bar and arm wrestling and getting into a big brawl and stuff like that, he brought a real kind of sense of scale to it; a real weight."

Marshall knew he needed a large performance for this role. He was looking for a dynamic general that Marshall believed the men would happily die for – a force of nature.

West enthuses easily about the part: "It's great because he's ideal general. He's adored by his men, and adores his men. He treats everyone really well and drinks and fights alongside his soldiers. It couldn't be more fun to play – until we had to do the cold bit."

The delivery of rousing speeches is something in which West revelled and excelled in equal measure. West explains that Virilus' role was to fundamentally rouse his troops into being prepared to follow their General into any situation, in West's words "goading them into hatred of this unknown, unseen enemy."

Resident comedian West frequently found a way to break the tension despite or maybe because of intense periods of filming. Being able to snap in and out of character meant West would deliver his lines with expert seriousness and then deliver a line off camera that would floor the crew.

Marshall: "As soon as you call 'cut' Dominic will crack a joke or something like that. David Morrissey was the same. Some of his best jokes came straight after you call, 'Cut'. He'll just run off a line or do something physical or whatever. They had the set in fits of laughter all the time."

And if West is pushed on what the ultimate appeal of the role of General Virilus was: "Well, it was the fact that I have a mud wrestle with Olga Kurylenko that really decided me that this was the sort of work I ought to be doing at this stage of my career."