He recalls: “They said, ‘There’s a murder case at the Old Bailey that we’d really like you to go and sit in on.’ I got there, and you have to go up the back stairs – and stand in a queue.”
Sadly for him, the trial was being heard in private that day. So Ben turned to a court usher for guidance. “I said, ‘Is there anything else on? Have you got a list?’ And he just went, ‘It’s not a cinema, sir.’ I skulked away.”
While he may have missed out on a real life day in court, Ben made up for it while playing Crown Prosecutor James Steel in Law & Order: UK (ITV1, Monday, 9pm).
This week’s story involves what appears to be the murder of an ex-vice cop. Prosecutors James and Alesha (Freema Agyeman) find themselves in a battle with a formidable defence barrister as they struggle in court to establish the truth of what actually happened.
“We came to an arrangement early on in the filming that I would have a camera on me and the person in the witness box would have a camera on them for the cross examination, so we would both be able to talk and overlap each other, which gives a real energy to filming.
“Because you are in a room full of people, like an audience, and there are just two of you going at each other, there is definitely an element of theatricality to it.”
Playing a barrister, he has to wear a wig in court. “It is made of horse hair and is very uncomfortable. I was given it for the first episode and then they measured my head and gave me this brand spanking new one.
“And I went, ‘No, no, no, I want my old wig.’ My wig has its own TV career, it has been worn by so many actors. There are loads of names in it that have faded away from the sweat. The only one I can read is Alan Davies, who wore it in The Brief.
“It’s ancient and they hire it. So I said, ‘I want that wig back. Take it out of my wages.’ So I got it back. It fits as well, as much as they can. They’re really itchy and hot.”
Ben is a big ban of the original American Law & Order series. “I was quite sceptical, originally, when my agent phoned with it as an idea. Purely because I loved the American version so much and I didn’t know if it could translate and be accepted.”
As fate would have it, he was actually working in New York at the time, about to open on stage Broadway in Les Liaisons Dangereuses. “The scripts sat in my in-box. Then my agent phoned and said, ‘Have you read them yet because they’re going to fly over and meet you.’ So I read them and just fell in love with it. I thought the adaptations were amazing.
“It’s hugely successful as a format – to have a body found and then see that right through to prosecution, or not in some cases.”
He adds: “I absolutely would hate to stand up in court. It just must be completely, totally, terrifying. Whenever we film those court room scenes and we have people in the witness box, suddenly there is a room with 50 people looking at you. It’s such a strange environment.
“But I really love that my character is so principled and decent and moral. He doesn’t side-step the law to achieve the results that he wants. I’ve had a career of playing deeply duplicitous people whose major drive is their sex life, and it’s so great to have someone who’s like a beacon of truth and sees society as a good place.
“His quest for the truth is what will be so compelling to watch. It is justice at whatever cost for James. He is so blinkered in his quest for the truth that it even destroys his personal relationships.”