Were you very involved with the casting?

The bit of casting that I'm chiefly responsible for is John Thomson. The character of Charlie that I'd written was an aging public school boy. Very louche, slightly lecherous, dissipated, but posh.

We looked and looked for someone and talked about various names, but no-one sprang to mind. We wanted a slightly more decadent Nigel Havers*, ten years younger. I'd worked with John Thomson once, and he just popped into my mind. He didn't set everyone alight initially, but he was funny, and I quite like writing humour.

But he came and did a really stunning audition. He dressed up like a barrister, came in character, and made the part his own immediately. It changed the nature of the character considerably. He's become a far funnier character, it's really added an extra dimension. I'm really delighted with that.

Was Don Warrington one of your casting decisions?

"We very deliberately wanted to cast a judge from an ethnic minority."

I think he might have been Gordon Newman's idea. We very deliberately wanted to cast a judge from an ethnic minority. There is a certain amount of pressure from the BBC, quite rightly so, to have a proper representative mix, but then an ex-colleague of mine is the first British High Court Judge who's a black woman, so I think we have to portray the reality.

There's a lot more judges from ethnic minorities, a lot more female judges, and a lot more young judges. Because judges have to serve 25 years before they get their pension, and they have to retire at 70, they've got to be appointed by the time they're 45 for full pension rights. We're trying to reflect that.

There's a wider age range in this drama than usual, with actors like Don and Paul Freeman in major roles.

Paul Freeman I didn't know very well, but what interested him was he'd been in E.R. I thought, we're under huge filming pressures, we've got to film seven minutes a day, in a precinct, so we're going to need people like Paul who've been there before, who've seen it, and who can be a steadying influence on the younger actors as well as turning in a terrific performance.

I'm really delighted with him. I really wanted to cast across the age range. There's huge pressure from the BBC to keep everyone as young as possible, and I don't want to forget that the bulk of our audience is middle-aged or older.

Quite honestly, I wouldn't watch a show that was nothing but youth because it wouldn't feel like any reality I'm in. And I'm damned if I'm going to write TV I wouldn't watch myself.

Can you tell us about the show's future?

We're doing twelve episodes next series.

It was always assumed that this was a potential long runner, a sort of Casualty/Holby. I've been asked to be the show runner on series two. This means I'm point of contact with the actors, running that creative end of it. I'm writing five of the twelve scripts and trying to build a team of writers.

"The challenge is to make every episode really good."

The challenge is to make every episode really good, to keep the story beating along but also have lots of serial stuff for a mass audience.

Would you say it's more of an American-style show in structure than a British one?

What separates us in quality from American drama quite often is, for example on a long-runner like Holby or Casualty, most of the writers just drop in for an episode or two and drop out again, and it's not that effective. You get by, but it doesn't lend itself to high standards.

The only way we'll get really high standards, and compete with the best American shows is if we build teams of writers who dedicate their lives to shows. It hasn't traditionally happened in Britain, but I'm making it happen on this show. I think that's the way that we'll build quality in the future.

We've got some really interesting writers including a Scottish guy called James McIntyre on series 2. He's a former Scottish lawyer who ended up in prison on firearms offences.

I'm trying to find people with huge passion and with something to say. In television, we've lost the single drama, we've lost the places that writers used to go to have their voice. That's what I came into television for, and I've ended up clowning round in series television thinking, "Where have all these opportunities gone?" Well, we have to make them in series television, and that means doing very good drama.