But the makers of Sky Atlantic’s Britannia starring David Morrissey, Mackenzie Crook and Zoe Wanamaker took a more imaginative and freewheeling approach to their costume creation. 

The series is set approximately 2000 years ago when the Romans are attempting to stamp their bloody authority on a tribal land made up of Celts and Druids.

“We had a great advisor who came to chat to us one night. Quite early on during the first bottle of wine he said ‘No one knows anything about the Druids or what happened after the Roman invasion,’” explained Tom Butterworth, co-writer of Britannia.

He was speaking during a panel discussion following an RTS screening of the first two episodes of season two, which makes its debut on November 7th. 

Added producer James Richardson, whose company Vertigo Films makes Britannia: “Historical accuracy was never part of that process. As Tom said the historical advisor did actually say ‘We know about 40% of what the Romans did, about 20% of what the Celts did and we know nothing about what the Druids did so you can do what you want.’”

There was, however, a more serious side to the fantasy show that has drawn comparison with Game of Thrones, said Jez Butterworth, Britannia’s main writer and the playwright behind such acclaimed stage plays as Jerusalem and The Ferryman. 

He said: “In all seriousness Britannia is about one religion dying out and another comes along – the massive tectonic shifts in faith around this time as one set of gods bully the other lot off the ball.

“That was the reason for me wanting to do it. To have characters who were under those kind of pressures, where their entire world of belief is crumbling and under threat.”

For both Jez Butterworth and film maker Richardson, whose credits include Monsters and Bronson, Britannia represented their first foray into television drama.

Butterworth told the RTS that the experience of spending ten or 20 hours writing one character was liberating.

“My plays are pretty long but they’re not that long. That chance to pick up something and make it run and run is something I’d never attempted.

“In film it’s over before it’s even begun. It’s like a haiku. Films keep getting shorter. When I started out there were 120 days, they’re 90 now.

“Writing Britannia was completely different, all the rules are different.

“We didn’t know what we were doing in the first series. We learnt as we went along.

“That is such a blessing to be presented with. Hopefully you get it right enough that it’s worth continuing with.”

His brother Tom, who has worked on TV shows such as Ashes to Ashes and Silent Witness, guided Jez through the process of writing for the small screen.

Tom Butterworth loved the scale of Britannia, a co-production with Amazon Prime Video. “I’d never worked on anything as big as this before,” he said. “To have that big a canvass and that number of Lego pieces to play with was amazing.”

Britannia is set in a brutal, macho world full of blood, violence and bizarre rituals and invariably male gods. But cast member Annabel Scholey, who plays Amena, (queen-in-waiting of the Cantii tribe) said she was attracted to the series because the female characters were strong, independent women.

She told the RTS that she wouldn’t have been interested in playing Amena had the part required her to be “a bodice- ripping prop for a man.”

“That’s not why I became an actor,” Scholey said. “She’s equal to the men, if not greater.”

She particularly enjoyed the show’s dry humour. “The scripts were so refreshing. You’re in a big period dress and to have the freedom of speaking quite colloquial, hilarious dialogue is brilliant.

“The juxtaposition is not what you’d expect. There is no Jane Austen here.”

The RTS screening of Britannia 11 and panel discussion was held at the Curzon Cinema, Shaftesbury Avenue, London on October 29. The chair was journalist and broadcaster Caroline Frost. It was produced by the RTS in conjunction with Vertigo Films.