Merlin’s co-creators have explained why they needed to “Grow up the show” and make Series 5 a more mature and darker story.

Executive producer Johnny Capps told SFX: “In episodes one and two we’ve got the northern plains, we’ve got snow. We’re being ambitious; each year we push the look of the show. And script wise we’re telling multi-stranded stories. We needed to grow the show up a little bit.”

“It’s a bit more adult and it takes to the characters to new places,” agreed co-creator and executive producer Julian Murphy. “They’re older. Take Gwen – she has to be a mature queen of Camelot now and you see stories where she plays the politics of that role in a very sophisticated way.”

Some have wondered if Merlin may be drawing from Game of Thrones. However Capps denied any influence: “I hadn’t watched Game Of Thrones! Then I noticed they had snow and I thought everyone’s going to say ‘you did snow because Game Of Thrones did snow!’ But there’s no such thing as an original idea, is there?”

He added: “If you look at Game Of Thrones… it’s nearly four times our budget! Does it make a difference? Yes, a bit; we probably reject three or four stories a series on the grounds that we simply couldn’t do it. We have to work within the world that we have. We have a budget. Our CGI capacity gets bigger which helps, so every year we put more on the screen I think. But practically there’s a line in the sand that we can’t go to.”