As Law & Order returns for a fifth series, Peter Davison joins the crime drama as the head of the CPS…

What can you tell us about your character, Henry Sharpe?
“I think he’s fairly straightforward. He was described to me as a nice guy who is just doing his job. For the most part, he’s in charge of the two characters, CPS regular Alesha and new boy Jacob, that do all the hard work in the courtroom. He usually has to calm them down because they show signs of getting personally involved. So he’s a moderator, a devil’s advocate. And he has a habit of cracking very bad jokes!”

What can you tell us about the opening episode?
“It’s complicated. It’s one of those cases where you don’t know who to go for.”

Do we see conflict between the police force and the prosecution over the course of the series?
“There are a couple of times where it comes up, yes. There are occasions where we realise that Henry is under pressure from above; for instance if they are going for a verdict that they eventually don’t get, there are all sorts of powers that be that come down on his head. Henry’s job isn’t just to moderate between his two barristers, it’s also about moderating between himself, the CPS and the people who pay the bills.”

Did you do most of the filming in London?
“Yes in and around London. Out on location they do a lot of what they call ‘guerrilla filming’; you just set up the camera and film the scene with the public walking by. Occasionally, people will turn around and look at the camera and look at you and stop for a few autographs! But for the most part people are fairly used to it so they just ignore you and get on with it.”

Were you a fan of Law & Order: UK before you joined the cast?
“What I like about the show is that it’s not about these people’s personal lives, it’s about the cases. There’s a terrible tendency in TV to turn everything, no matter what the setting of it, into a kind of soap, but this isn’t like that. You’re not going to tune in one week and discover someone’s having an affair with someone else!”

Law & Order: UK returns on Sunday July 10 at 9pm on ITV1