Welcome to Oakdrive Nursing Home. "Today is Tuesday," reads a notice on the wall of a shabby room. "The next meal is dinner" states another, below which a third reveals that tongue salad is on the menu.

Elderly residents are nowhere to be seen, which isn't surprising as this old people's home has been created for BBC1's new Newcastle-set detective series 55 Degrees North.

On a bitterly cold day last February four months of filming was nearing its end. The production was occupying a former education development centre in Benwell that lacked both heat and running water as the setting for the nursing home.

Between takes, everyone huddled around electric fires and debated whether to brave the cold and go outside for a cup of hot tea at the catering wagon or to visit the portable toilets. Throughout, actor Don Gilet remains relentlessly cheerful, chatting to fellow actors and technicians rather than retreating to his trailer in the car park.

He's been working six days a week away from his London home, returning every other weekend "to make sure no one has broken into my house". Until now, he's been best known as one of the cast of BBC2's Babyfather. In 55 Degrees North, he takes his first lead role on TV. He's the star who's carrying the drama, which also features Dervla Kirwin and a cast of North-East actors.

He says it's "an ensemble thing" but can't deny that his is the face being used to sell the show. "I am very lucky - and all those platitudes," he says. "In terms of volume, I say more than anyone else. I've never done anything as big as this. They pay me as the main guy. I try not to feel the extra responsibility, I'm not that responsible.

'I suppose every actor is looking for the next break from the theatre point of view, or TV, or film. I think it's fair to say I was ready if one came along that I was right for."

His role is Detective Sergeant Dominic "Nicky" Cole, a London detective relocated to Newcastle to work the nightshift - hence the series' original title Night Detectives - after he blows the whistle on police corruption.

The Midlands-born actor has been a working actor since leaving drama school in 1989. Babyfather offered his first real test of intense filming, which proved valuable for shooting six hour-long episodes of 55 Degrees North in just four months on location in the North-East.

First, though, he had to get the part. "I saw the script and thought, 'I'm right for this' and loved the writing, and could picture myself doing it," says Gilet. "That's where it gets more dangerous, seeing yourself doing something. There's a higher place to drop from if you don't get it."

Happily, he did get the part, culminating a year spent in the police and running. He was in another cop series, The Bill, and then played an athlete who died on a run in Silent Witness. He trained with a real athlete to play the 100 metre sprinter, which came in handy on 55 Degrees North as the first thing he filmed was a long chase on foot through Newcastle city centre.

He enjoyed doing the action scenes. "I worked with the stunt man. He said, 'Do you want to do this?'. There was a lot of nervousness about allowing me to do it. I ran over this car - from bonnet to back, landed safely and continued the chase. I did all that myself," he says proudly.

His only other visit to Newcastle was in a stage production of The Clandestine Marriage with Nigel Hawthorne some years ago. He didn't get to see much of the city this time. "I tried to get out but I had so many pages of dialogue to digest overnight. That was my priority. I only felt I dare go out if I didn't have that much to do the next day," he says.

Despite the distinctly unglamorous and hectic schedule, Gilet was the life and soul of the party on set as he is on most jobs. "It's just like being a kid in a toyshop," he says. "It's one of the things you've always wanted to do and it's here in front of your eyes. I enjoy it, everything I do. I'm having a load of fun. It's not feeling like work. It's a rare opportunity and hasn't happened to me before."

He refuses to pick out the best bits, saying the whole experience was a highlight. "The only thing I didn't like was the cold and the running," he adds.

His co-stars pay tribute to his smiling personality and easy-going approach in the face of a heavy workload. One scene wiped the smile off his face. He had to get naked, be rubbed down with baby oil and run into the street with his trousers round his ankles after Nicky visits a brothel to gather evidence.

"It means stripping off and getting a massage. I've done a nude scene before in Babyfather, but there was nothing erotic there. While this wasn't a love scene, it was still very intimate. So it was quite a nervous experience for me and everyone noticed I wasn't joking about it or talking to people like I usually do," he says.

"To make things worse, I'd only met Tracy Whitwell, the actress involved, that day. She tried to make me feel better by saying she wouldn't look down."

He finds watching completed episodes of 55 Degrees North equally difficult. "I have to stop looking at me - this is the guy carrying the show. In episode two the characters are more bedded in and there's not as much exposure on me as in the first one."

* 55 Degrees North begins on BBC1 tomorrow at 9pm.