How would you describe your character in the show?
"Johnny Proude has come from a Northern mining village and his mum has brought him down to try to get him away from all the trouble that he's had in his past. He comes down to the house and has a bit of a love affair with the maid, Ivy. Then it all goes a bit wrong for him! It's a nice character to play because he's quite a normal guy at first, and then he sort of turns at the end. You see a different side to him."
How does his relationship with Ivy progress over the three episodes?
"In episode one, they first meet and you can tell that there's something there. Every time you see them, they're looking at each other from across the hallway. It gradually gets a bit more romantic and a bit more passionate, and then she helps him with something in the third episode. She helps him out when he really needs her."
Johnny is keeping a dark secret in the show. What hints can you give us about that?
"I don't know how much I can say! When he was living with his mum, he got into quite a few brawls in pubs, so that might have something to do with it!"
Did you enjoy filming a period piece?
"I absolutely loved it. You go on set and you're in a place that you've never been before. You're sent back to the 1930s. It was so different, but I actually preferred it [to a modern-day setting]. You're not playing someone close to you, you're playing someone so, so different. You can get your teeth into it a bit more."
Was it a challenge to play a character so removed from yourself?
"Yeah, definitely. Just playing a character that's different to you is a challenge. But to do it in that time period, you had to learn about what they did, their mannerisms, what they did when they woke up and so on. There's a lot of things to go into that normal people wouldn't do these days!"
Did you research the period before filming began?
"It was quite helpful actually because one of the production girls had loads of books from the 1930s. She handed them out to the cast, then we each read one and passed it around. It was great, because you learnt things every day. Having Jean Marsh and Eileen Atkins on set was great too because they were the writers of the original series and so they knew exactly what should happen. So if there was anything wrong with the script, they would mention it, and help you out."
How familiar were you with the original version of the show?
"I'd never seen it before. When I first told my mum that I had a meeting for it, she was like, 'I used to love that programme!' I told her that Jean Marsh was going to be in it and she was amazed. She didn't know how old Jean was and she didn't understand how Jean could still be in it, if it was continuing on from the old series. But it was mad, because I started watching it when we were filming the new episodes in Cardiff. I had a break and it was on ITV2. I started watching it and I just got more and more interested. I watched a couple of episodes and got properly hooked on it! I was hooked by the stories, and hopefully that's how the audience should feel after watching these new episodes."
Is it daunting following on from such a well-respected series?
"Yeah, definitely! Jean Marsh was on The One Show the other day and she said that the original had something like 20 million viewers! I was like, 'Oh my God!' But I think we'll do it proud."
How was it working with original star Jean Marsh?
"Jean was great. She's probably got the youngest mind-set in the cast! She's always coming out with these ridiculous and random stories. She's so funny to work with and she just makes everyone feel at ease. Keeley [Hawes] and Ed [Stoppard] were the same. Everyone was just great to work with. Everybody got along and helped each other out."
Would you be interested in returning to Upstairs, Downstairs in the future?
"Definitely. It's great to be part of something like Upstairs, Downstairs, with the following that it's got. I just think it would be a great thing to have with me. I'm sure that people will want another series, once they've seen this one!"
Upstairs, Downstairs begins on December 26 at 9pm on BBC One.