Robert Eggers felt historical accuracy was essential in 'The Northman'.

The 38-year-old director has helmed the historical epic that is set during the Viking period and explained that he wanted the movie to be accurate even if little is known about the period.

Robert told The Playlist: "It's just the approach I enjoy. I enjoy the act of researching the way some people might enjoy skiing! I just like it.

"But it's also a kind of discipline, and if the goal is to get inside the head of people in the Viking Age, then the way they expressed themselves in their clothing and their architecture needs to be right too, I think. And also, the atmosphere is an accumulation of details; it's why we have the landscapes and the elements.

"The more visual information that can be on the edges, I think, makes the world more credible. But you're right, we don't know a lot of things about Vikings, and I tend to choose the academic consensus."

'The Northman' is Robert's biggest film to date and he explained how he was able to improve the picture through test screenings.

'The Lighthouse' director said: "I knew I was not going to have final cut, and so in post-production, that's where things were new and more difficult for me.

"For example, the test screening process – which, by the way, I learned stuff about the film! It made the film better. Did I like it? No. Did I like the studio pressure and the studio notes? No. Did they make the film better? Yes. Did I need it to make the film better? Yes."