Sian Clifford, who plays Diana Ingram on Quiz, talks about preparing to play Diana, why she enjoyed the scenes between Diana and her brother, and what she thinks about the Ingrams' criminal conviction.

Q: How did you get into character for this role?

A: My main source material was a documentary that was made about a year after their conviction. It was an hour long, and it was a documentary at home with the Ingrams. I watched that a lot. Obviously when we were filming stuff that was in the studio, I watched a lot of that footage, repeatedly. Matthew [Macfadyen] and I would often watch it together. It was a lot of that, but, honestly, James [Graham]'s script gives you so much and really captures something of their essence as human beings and so that was really, really useful and actually made it easy to lean on.

I did a ton of research before we started shooting, and I watched her for hours and hours before we started shooting and then every single day I was watching her. But for me, in terms of getting into character, it's always about a feeling. I used to be so in my head about these things, and I've completely binned that. I don't think it's helpful actually for acting at all to try and be controlling about these things. So, yeah, just watching her and trying to get to the heart of her, rather than a caricature, and any version of what had been written about her in the press or anything like that I completely ignored.

She's a real introvert, Diana. She's very shy, so she doesn't give you much, so you really have to use your intuition, and I got this impression, weirdly, that there was something really sweet about her and, when I did finally meet her right at the end of filming, that is the number one thing I would say that kind of exudes out of her, so I was so grateful to have just picked that up from watching her over and over. She was portrayed as this Lady Macbeth character in the press, and she does have hard edges just like the rest of us, but she isn't this malicious character. There's something so soft and kind about her, and she adores her children and she's a wonderful mother. And even the way that her and Charles interact, it's all very gentle. They really have such an extraordinary dynamic of acceptance of one another, I think.

Read More: Meet the Real-Life Diana and the Rest of the People at the Heart of Quiz

Q: How would you characterize Diana and Adrian's relationship?

A: Again, so much for free in the script. And Adrian is a consolidated character, so Diana actually has two brothers, Marcus and Adrian, and they've been consolidated for dramatic purposes, and with the permission of the Ingrams... I loved those scenes. They're a really funny aspect of the show, for the most part, just how he sort of interferes in Charles and Diana's relationship. Every single scene, more or less, when Adrian appears, Charles is talking about getting quality time with his wife, and I just remember reading it in the script and just finding it so funny. It was really fun to film those scenes, and Trystan [Gravelle] is someone I've known for quite awhile, but we've never worked together, so it was really, really fun to get to work with him. You just play the scene, the truth of the scene, straight down the line, and I do think they're some of the more lighter moments in the show, and I really loved filming all of those, like the pub quiz. That was one of my first scenes that I filmed actually, and it was really fun. Although that pub, oh my God, it was so hot and it was full of smoke. It wasn't very pleasant, so everyone was taking lots of breaks outside whilst we were doing that one.

Q: Can you talk about filming the scenes in the studio when you were in the audience? How challenging was that?

A: That was the hardest thing to film for me because I felt very isolated from Matthew, which is exactly how Diana would have felt, so it was perfect really, perfect conditions, and they had of course built this to-scale replica set, with full lighting and sound rigs, so it was like being on the show. I mean, it was absolutely amazing, and so it was really fun. But a lot of my stuff I did out of context because the boys [Matthew Macfadyen and Michael Sheen] couldn't be there for whatever reason, and so I think a lot of those reactions I had to actually just film -- they'd be like, "Oh, it's this bit," and I'd have to just improvise. Yeah, a lot of it is that, and that's from me studying [Diana] on tapes and things like that, so I did find that quite hard.

And some of the time they filmed me when I was actually looking at them, re-enacting the scenes. What was brilliant is the TV screen that I look up to -- so the cameras that we had on set [for the Who Wants to Be a Millionaire? replica set], they were live and operating, and so I was getting a live feed, from that camera onto the TV, of Matthew, which was absolutely incredible. There was one point, it was just pointing to like the back of Michael's chair or something, and I said, "Is it possible for me to actually see Matthew as I would see him?" and they were like, "Yeah, of course," so they swung it onto him and that was really helpful. And then you're off, you're away, because they would play the music and it would be really loud and it would reverberate through your body and it is designed to make you feel unsettled, that music, so you do. So it was really fun, but it was definitely challenging to try and capture the drama of it and make it feel like a heist.

More:Watch the reconstruction of the Who Wants to Be a Millionaire? set:

Q: I read that you aren't so good at quizzes. Is that true?

A: I did a quiz during isolation, which my team won. It depends on the category, right? It depends on the questions, so if it's lots of film and TV, then I'll be fine. But if you ask me about, I don't know, politics and gardening, I'd be a disaster. Don't put me on that team! But picture rounds [picture quizzes] -- I love picture rounds, probably because I have a visual memory, so I find those things quite easy to recall.

Q: After being involved with this production, do you have some doubt about the Ingrams' guilt?

A: I definitely have a lot of doubt as to whether they should have a criminal conviction. Regardless of what went on, I don't think you can prove beyond a reasonable doubt that he didn't know the answers to those questions. I think, as to whether they're guilty or not, it's as ambiguous as ever. We presented another side to the story, so I think there's room for doubt. I think we ask a lot of questions, but we don't necessarily give you answers, and it's up for us to decide.

But the real thing that's come from this for me is that we shouldn't be so quick to judge people. I think we need to examine how the press behave, in terms of their pursuit of a story and the harassment of people. It's disproportionate, the response to this. It's a game show. I know it's a million pounds, but it is a game show, and you had people with a lot of money going after people who had nothing. For me, I'm coming away with a huge amount of compassion for the human beings involved, regardless of whether or not they did it.

Stream full episodes of Quiz now on amc.com and the AMC apps. Unlock more with AMC Premiere: Binge the entire series, ad-free. Learn more at amcpremiere.com.

Plus, find out how playing Chris Tarrant changed star Michael Sheen's perspective on the Ingram's guilt. "When I was actually there on the set, you think, 'How on earth could they have gotten away with this?,'" says Sheen. Read now.