FIRST there was Holmes and Watson, then there was Starsky and Hutch, Cagney and Lacey, Danger Mouse and Penfold.

All ace crime-fighting duos, but none had copyright on the immortal line, "Get your trousers on, you're nicked."

For that, the world had to wait for London coppers DCI Jack Regan and Sergeant George Carter, first played by John Thaw and Dennis Waterman, and now by Ray Winstone and Ben Drew, aka the singer Plan B, in a movie reboot of The Sweeney.

Directed by Nick Love, and written by Love and Glasgow's John Hodge (Trainspotting), the 2012 version of the Flying Squad brings the boys in polyester slacks bang up to date, giving them Apple Macs and paperwork in place of dodgy haircuts and Ford Granadas.

Drew wasn't born when The Sweeney first aired between 1975 and 1978. While it has had a long afterlife as repeats, it still wasn't quite for him. "I had a prejudice towards black-and-white films growing up. They seemed as cool as all the stuff we had in colour."

Winstone cannot only remember the series, he was in one of the episodes, credited as "youth". He was impressed by the show, then and now.

"It was groundbreaking TV. You had Dixon of Dock Green and Softly Softly, great shows in their own right, but [The Sweeney] was the first show I can remember that was down and dirty and we could all kind of relate to it in a way. Well, where I lived you could, anyway. It was real."

He traces a direct line between The Sweeney – showing some policemen to be as willing to defy the rules as criminals – and razor-edged crime dramas such as The Wire that win awards today. "It may be updated, but it all for me came from The Sweeney."

The modern Sweeney breaks a few rules of its own, chief among them having the older man, Winstone, as the love interest. For Nick Love, this was all part of keeping the film real.

"Ray is in his early 50s, to try to sell him as a kind of a ripped 35-year-old wouldn't work, so I have played on the big belly – Ray loves all that – and I have played on the chain-smoking and womanising."

Winstone is quite happy to make the sacrifice of being a sex symbol later in life. "I'm a 55-year-old fat man. I think it's the way you treat women that makes you sexy. You've got to be genuine, a bit of a gentleman and a bit of a rogue at the same time. But if you try to set out to be that, you're never going to achieve it. I don't know how that works. Ask ladies. I haven't got a clue. But if I am [a sex symbol], fantastic, I love every minute of it."

During the six years it took to get the film up and sprinting, Winstone was always going to be Regan, but the filmmakers couldn't find the right fit for Carter until Drew, the musician turned filmmaker (Ill Manors) came along. It was an interesting match in other ways, because Winstone, the star of Scum and Quadrophenia, was once the angry young man of acting that Drew is portrayed as today.

"I learned a lot as an actor," says Drew when asked about working with Winstone. "I was way out of my comfort zone. There were times I felt I wasn't as strong as I could have been and Nick and Ray would pull me up on it. Not just pull me up on it and tell me I was doing it wrong. Ray was always there to offer me another way of looking at it, thinking about it and doing it."

Winstone was equally impressed with his 29-year-old co-star. "We had many times when we used to just sit down and have a chat about what's happening in the world. I was lucky enough to have a kid with me who is intellectually up with what's going on in the world, puts his money where his mouth is and goes and does something about it. It livens you up a bit. Brings you into the 21st century."

As if to close the circle, Winstone remembers a time when he was the junior acting partner to John Thaw, first in The Sweeney, later in the film Masculine Mescaline, and then in television's Kavanagh QC. He recalls in particular one bad day at the office. He was rehearsing for Nil By Mouth at the time, in a play at the Royal Court, and working on Kavanagh. "It was gone, I was dead, it was my body saying I've had enough."

There was one 15-minute scene when, try as he could, Winstone couldn't remember a line. Thaw was "terrific" about it, and watching Thaw learn pages of lines every day only added to Winstone's admiration.

"He was a complete and utter professional, but a good guy with it. I learned something from him about being humane about things, giving people time. A very special man."

Winstone is up for a Sweeney sequel. Drew, having just released Ill Manors as well, is up for a break.

"One night out with us should sort it," laughs Winstone. "Musicians, they can't hack it."

Spoken like a true DI Regan.

The Sweeney opens next Wednesday