Sheridan Smith reveals the highs and lows of playing the long-suffering spouse of gangster Ronnie Biggs in ITV1’s Mrs Biggs (Wednesday, Setember 5)…

How much did you know about the 1963 Great Train Robbery before becoming involved in ITV1’s new five-part drama?
“I knew bits and bobs, but there was a lot I didn’t know. One of the things I discovered was Ronnie Biggs wasn’t even a big part of it. He was blown up like he was the mastermind of it all, but he wasn’t that great a crook at all!”

Why do you think it’s a story that continues to fascinate us?
“The fascinating thing is that first they managed to pull the robbery off – it was huge at the time – and also that Ronnie went on the run for so long. But nobody knew anything about his wife, Charmian, who went on the run with him. That’s why I think this is so important. I had no idea what she went through.”

What do you think viewers might find most surprising about Charmian’s life-story?
“I had a preconceived idea that she was a gangster’s moll, but when I read the scripts I realised I couldn’t be more wrong! She was an educated girl who, ironically, met Ronnie on a train and fell madly in love. It’s unbelievable what she went through – becoming a single mum when Ronnie went to prison for the robbery, then going on the run and fleeing to Australia with him when he escaped prison. She also lost her young son in a car crash, and later divorced Ronnie after he fled to Brazil and got a girl there pregnant. The heart of Mrs Biggs is a love story.”

Has it been a difficult and emotional role for you?
“I’ve had to go to some dark places, but it’s been an incredible part to play. I hope I’ve done Charmian’s story justice. It’s obviously different from what I’ve done before. That was terrifying in some respects, especially playing a lead, but it was great to step out of my comfort zone. It was a really, really special job. I hope people like it.”

You spent quite a bit of time with the real-life Charmian Biggs in preparation for this role. How was that experience?
“When I first met Charmian I was quite star struck! I had watched old footage and read all about her as part of my preparation for the role – so in some ways I felt I knew her inside out. It’s not often you meet the person you’re going to play. I was nervous and worried she might not like my interpretation, but she was so lovely. She put me at my ease and was really helpful. We’ve become close.”

You play Charmian from her late teens until her early thirties and take in several eras of fashion. Was that fun?
“There’s a huge age jump over the five episodes, but it’s really clever how Make Up and Wardrobe aged Danny Mays – who plays Ronnie Biggs – and I. It was fun, and the hair, make-up and costumes helped me get into the feel of different periods, from 50s to 60s to 70s. I felt completely different to myself; and more like Charmian. I loved wearing the dresses, hairstyles and make up. I think my favourite was the sixties.”

Although the story is dark, was it a fun job?
“I am so thrilled I was chosen for this role. Some days were more draining than others because we had some really heavy scenes. But there are also lots of happy scenes and there was lots of fun on set. One day Danny and I got the giggles trying to shoot a scene where Ronnie had plastic surgery after he broke out of prison. Danny’s face had been taped back, but it kept pinging off in the middle of filming. I looked at him and he had this thing dangling from his eye and we both just lost it and fell about!”