It’s sure to be an emotional week in Merlin as King Uther perishes after saving his son Arthur. Katie McGrath, who plays his wicked daughter Morgana, reveals her shock role in her father’s death…

Morgana seems even more evil in this series. Do you agree?
“Well, I’m the worst person to talk about this because I don’t really believe she’s evil. I think she’s more a victim of her circumstances. She was persecuted in a kingdom that if they knew about her magical ideas, they’d have killed her. She and her father King Uther are actually very similar, but have very different viewpoints on magic – he’s totally against and she is for it. She’s not bad, she’s just confused!”

In this week’s episode, when King Uther defends his son Arthur from an attack by sinister circus-master The Gleeman (Phil Davis), he’s gravely wounded. But does Morgana play a role in her father’s eventual death?
“Yes, she does something that helps to see him off, but it’s not entirely her fault! It’s a means to an end. It’s done in a kind of Jack Bauer-in-24 situation – sacrificing one for the many. Morgana makes tough decisions and that’s why she’d be a good ruler if that ever happens. She’d definitely be better than her half brother Arthur!”

Do you think viewers will see her good intentions?
“I hope she comes across as a sympathetic villain. I want people to watch her and think, ‘Well maybe she’s going about it the wrong way, but I can see her point.’ That’s what I’m trying to get across.”

Are you enjoying playing her dark side in this series?
“Who doesn’t love a bad girl? After playing her for three series as good, bad and evil, I can say that bad girls definitely have more fun! I’m enjoying this series so much because she’s got a clearer path. She’s not just sitting in her cave cackling, she’s trying desperately to do something she believes in…”

What reaction do you get from fans?
“When little kids see me they say, ‘She hurt Merlin!’ So I have to reassure them by saying in a kindly voice, ‘I’m not going to hurt you, I promise!”

*Merlin is on Saturday, October 15, at 8.15pm