Speaking to CultBox on the fantasy drama’s set in Cardiff last month, McGrath joked: “I could lie to you, but it’s much more fun being bad that it is being good, I swear to God.”

The actress explained: “I mean, no, Morgana was great for those years but this is really who she’s supposed to be. She’s not acting anymore, she’s not pretending to be the little princess, she’s not trying to hide anything, she is just who she is. And with that comes this amazing confidence and power. Who doesn’t want to play this confident, powerful woman?”

Series 4 is expected to launch with a double-bill on BBC One next month.

> Order the Series 4 Volume 1 DVD on Amazon.

Watch our intervew with Katie McGrath…