PROLIFIC, controversial and original in equal measure, Russell T Davies is one of the most successful writers currently working in television.

Due to the massive amounts of praise heaped upon his work, which includes Queer As Folk, Bob And Rose, The Grand, and of course, a certain prime time science fiction drama, he's a man used to dealing with huge stars, big budgets and glamorous award bashes. That doesn't mean Russell T Davies takes swanky surroundings for granted.

"Posh in here, isn't it?" he says, eyeing the foyer of a luxurious London hotel. "Of course, I hang around in here all the time," he adds chuckling, before laughing some more and getting stuck in to the packet sandwich in front of him.

We're here to talk about the new series of Doctor Who, the fourth since Swansea-born Davies revamped the franchise in 2005.

"I find this time, just before a new series, really scary," admits Russell. "We just want people to watch it because it's lovely. I love it. It's well known that I've always loved Doctor Who, but I do, I really do!"

Until Russell's intervention, it's fair to say Doctor Who's glory days were long gone. The tenure of Sylvester McCoy, the last man to play The Doctor in a full series, wasn't held in the same regard as golden-era Jon Pertwee or Tom Baker, while after the axe in 1989 all but the most optimistic of fans had given up hope of the show ever making a return to our screens.

A whole generation of children had missed out on cowering behind the sofa when one of the Time Lord's many foes - like the infamous Daleks - appeared on screen, and knew nothing of the sometimes hammy acting and low-budget special effects devotees loved so dearly.

But there was still a great deal of affection for the character and his escapades; a fact proved when more than nine million viewers tuned in to watch Paul McGann become the eighth Doctor in a 1996 one-off TV special.

"We were careful and very aware of that when we brought it back," says Russell. "We knew there were lots of people who'd not seen it before. We were writing for them, really.

"All the elements of the show were there, the Tardis, the sonic screwdriver, but it was a clean start," he continues. "The dread was that mum and dad would sit down and watch the show, but the kids wouldn't because, let's face it, you don't want to do what your parents do when you're a kid, and anything they watch is automatically bad.

"That was a very big worry at first, but I think it was a cynical view of families. It turns out kids love sitting with their mums and dads to watch TV, especially 'event' television like X Factor finals and things like that.

"I just knew if we could create that sense of event every week we'd stand a chance of being successful and getting an audience. And I was right," he says, laughing.

The forthcoming series will see David Tennant play The Doctor once again, but he'll be joined in the Tardis by Catherine Tate. The TV funnywoman first appeared as Donna Noble in The Runaway Bride - the 2006 Christmas special. She loved the show so much she wanted to commit to a full run of the programme; something Russell thought would never happen.

"We had no idea Catherine was going to come back to us, none at all," he says. "We couldn't believe we got her for the special really, she's so in-demand. And not just that, Catherine generates her own stuff, she's a writer too, so she's always busy.

"It came about after Catherine had a meeting with Jane Tranter, BBC head of fiction. Jane rang me and said Catherine had gone on and on about Doctor Who and how much she'd enjoyed the special. Jane said, 'I might be mad, but if you ask her to do the series, I think she'll say yes.' "I thought it was ridiculous, but my colleague Julie jumped on a train to go and meet with Catherine two days later. I didn't go because I was busy saying, 'Don't be ridiculous, we'll never get her.' But Julie went and Catherine agreed to a whole series and cancelled all her plans there and then! She moved to Cardiff for nine months to film as well, which is some commitment."

Having started as a writer in the late 1980s with kids' dramas Dark Season - which featured a young Kate Winslet - and Century Falls, before moving on to Children's Ward and later the controversial and award-winning Queer As Folk, Russell has worked with thousands of actors but still puts The Doctor's latest companion among the very best.

"She's absolutely fantastic," he says. "That's why we wanted to bring Donna back and why I wanted to write more for her. Obviously Catherine can do comedy with her eyes shut, and there's a lot of comedy in Doctor Who, but when she hits the tragedy - and there's a lot of tragedy for her character in this series - Catherine gives the most stunning performance.

"Seriously, when I pack my bags on Doctor Who, I am knocking on Catherine's door and asking what we're doing next. She's brilliant."

Russell's praise isn't solely reserved for Catherine either. During our chat, he talks passionately about how hard the cast and crew work on the show, and how proud they all are of the finished product as a result. Star David Tennant gets his fair share of superlatives too.

"There's a danger we don't talk about David often enough," Russell explains. "He's so powerful, and brave, and scintillating as The Doctor, there's almost a danger of him blinding everything else. That's why we have to have an equal aboard the Tardis in the companion. Suddenly it becomes a different dynamic and we see David upping his game to compete with Catherine. It's amazing."

Of course, getting any storylines out of Russell is impossible. He and the rest of the production staff work very hard to keep pending plots under wraps, but what he will say is that there's a lot to look forward to during the 13-episode run.

"Well, there's David and Catherine on screen together, which is very special indeed. As an actress, Catherine's completely devoted to David. Every year we write stuff that pushes him, because we don't want him to get bored, basically.

"We never want him to have an easy life either, so this year there's more, darker material for David, but also funny stuff for him too because he's so good at playing that.

"I can say monster race the Ood are back, and they look fantastic, plus there are various other surprises, with everything building toward the most staggering climax you will ever see!"