What does series five hold for Gwen?

I’m thrilled because Gwen is a lot more glamorous this series. Now she’s queen she’s gone up in the world and her costumes are beautiful, sexy, off-the-shoulder numbers. It means I spend a lot more time being laced into corsets but after four years of shabbiness I’m not complaining! Oh, and look out for a really exciting storyline involving Gwen and Morgana…

What skills have you acquired in five series of Merlin?

Sword-fighting, although I’m always jealous of all the swashbuckling the boys do because we girls don’t get to do quite as much. I do more horse riding this series, which I love because we get to work with such stunning horses. Mine is white with a mane done to the floor – it’s like a Barbie horse.

Are you inundated with fan mail?

We don’t just get mail! We get fans from all over the world turning up at the chateau in France where we film from as far afield as Australia. One woman dressed up as Percival and knitted a chainmail cardigan with straps, cuff and cloak. She’d really gone to town. Merlin is now so popular there are often swarms of people with cameras outside the chateau and even in the chateau because it’s open to the public.

Is that distracting?

It’s a bit weird because you can sometimes have a huge audience watching you. But it’s also nice because they’re really excited to see you and obviously love the show – it stops it feeling like just another day at the office.

Isn’t it supposed to be a kids’ programme?

It’s definitely grown up as we’ve grown up and as the fans who watch it have grown up. It’s become a lot darker but it’s handled well: something terrible will happen but then there’ll be light-hearted banter between Merlin and Arthur.

What’s it like behind-the-scenes?

We’ve been working together for such a long time we have become like a family – not just the cast but the crew as well. We consider ourselves part of the crew: we’re Team Merlin. There’s nobody who’s more important than anybody else and everybody likes to joke around and have a laugh. That’s really important because it’s such a long shoot; you need that comic relief.

If Merlin carried on for another five series, would you?

Who knows? I’d hate to think of it going on without me because I’ve been part of it for such a long time. Then again, I became an actor to do a variety of different things so I won’t stay forever and ever.

And the rumoured Merlin movie?

That has been mentioned. It hasn’t necessarily been mentioned to me but I have heard people talking about it! It works well on the big screen so you never know.

Series five of Merlin continues on Saturday at 8:25pm on BBC1