The Selma star is dismayed actors of colour only have secondary roles in the show, and he thinks the show's writers and directors can and should do better.

"The fact that they put any ethnic minorities in that means that there should be space for bigger characters," he tells "Because you're not just saying, 'OK this is purely a white world, and here are very story-driven reasons why that's the case'."

"You are interspersing people of colour into it and so therefore it's a conscious decision to put them on the margins, as opposed to put them front and centre," he continues. "Even if, for whatever reason, it's a world in which people of colour in those stories are subservient, or they are more in a helper role, that doesn't mean they can't have prominent story lines.

"All you have to do is shift the focus to focus on those characters... There is absolutely no excuse in a show like that why there aren't more prominent characters of colour."

Game of Thrones is not the only show the 40-year-old is taking issue with - he also feels sci-fi series Doctor Who could feature a female or minority lead, considering the titular timelord is recast every few years.

"I think that is an absolute case in point, whereby I don't think there is anything about that character that is rooted in white maleness," he says. "There are going to be people who are going to resist, on the basis of tradition, but I think that's absolutely a character where, from a story point of view, it doesn't undercut the story in anyway."

But David has high praise for director J.J. Abrams after he John Boyega as a stormtrooper in Star Wars Episode VII: The Force Awakens.

"Trust me, there was resistance and the great thing is that some of that resistance was vocal, and yet it goes on to become one of the most successful films of all time," he continues. "It shows that you cannot continue to use the excuse of a potential ding in your financial renumeration as a reason not to do these things."

"What he (Abrams) did with Star Wars was fantastic, and he's the producer on (my new movie) God Particle as well, and our cast is myself, Gugu Mbatha-Raw, Zhang Ziyi, Daniel Bruhl... you know, it's a group of actors who are from everywhere.

"We can all, I think, hope that our future is gonna be more colourful than what our past has been, certainly in terms of cinematic depictions."