What can’t you miss?
The Wrong Mans. I started watching it, obviously, because my Gavin & Stacey co-star James Corden wrote it but it’s brilliant! I watched the second episode twice because it made me laugh so much.
What makes you giggle?
Downton Abbey. Ever since the Comic Relief sketch with Jennifer Saunders as the Countess, I can’t watch it because it makes me laugh.
What makes you shake your fist?
Question Time. I’ve been asked to go on it but I’m too scared. I’d either get really nervous and not know what I’m talking about, or I’d come over all compassionate and reveal too much.
What brings out the hankies?
I cried when Dexter ended. If I could be any character on telly, I’d be his police officer sister: she’s so strong. I’d run around shooting everyone, although I probably shouldn’t say that now I’m a mother!
Has your baby daughter Eva expressed any predilections?
The other night Strictly was on and she wouldn’t go to sleep but she was mesmerised by Julien Macdonald and his glittery costume. So I’m going to have to get him round next time she’s cranky!
Your dream dinner guests?
Peter Ustinov, Richard Burton, Elizabeth Taylor and Anthony Hopkins. And the finalists from The Great British Bake Off because they could cater. All I want to do is eat cake now I’m breastfeeding.
When do you use the off switch?
I went through a stage of recording Come Dine with Me and watching it constantly and I think I’ve overdosed; I can’t bear it any more.
What did you like as a child?
Agatha Christie. Being in a world where everybody would always get murdered really frightened me but I was fascinated by the costumes, the hairstyles, the Englishness of it all. To this day I’m obsessed with Miss Marple; I can’t wait until I get into my 60s and can play her.
You’re playing a glam 60s doctor’s wife in Breathless – it’s a long way from Stacey.
I love the part of Lily. It’s completely different from how people know me from Gavin & Stacey. And I look so different because I’d just given birth. Lily is desperate to have a baby so it was quite easy to play all of those emotions, having just become a mother myself. In the audition all I talked about was my placenta. They must have been like: “She’s perfect.”
Did you sneak Eva on set?
Before I started work, I said: “I’m going to be breastfeeding so whenever she needs to feed I’m going to stop.” I was like a lioness. So she was sitting behind the monitor, jabbering away to the make-up girls.
We’ll soon see you in Doctor Who’s 50th anniversary special. How was your Who debut?
I’ve always wanted to be in it so I was so excited. You don’t expect when you’ve just had a baby for someone to phone and go: “Do you fancy playing Elizabeth I?” I was recovering from a caesarean but I still got on the back of a horse with David Tennant. Just as we were about to ride off my husband drove up because Eva needed feeding: I had to jump off the horse and rip open my bodice. Fortunately, David’s a dad so he’s used to it!
Breathless in on tonight at 9:00pm on ITV