A villain is perhaps the last thing you'd call veteran Northern funnyman Tommy Cannon. After all, this is the cheeky comedian who, alongside longtime partner Bobby Ball, has graced Britain's television screens, theatres and even cinemas for the past 43 years.

"Oh, the enemies and the villains are always the best parts," Tommy remarks on his role as Mr Price-Hargreaves in upcoming play Big Bad Mouse, which arrives this week at the Theatre Royal Windsor. "They're always such great roles which really allow you to get your teeth into them."

But ask the usually eloquent entertainer to describe the play and he'll struggle. "It's not just a funny play or a funny comedy," muses the veteran comedian, who lives near York with his second wife, Hazel. "It's more just a very funny piece of material. See, the original 1970s' version of the play wasn't getting any laughs, so Eric Sykes had to add some humour to it. It virtually destroyed the play, but made it a big success. The result is it's very hard to categorise."

The plays sees Ball's Mr Bloome bossed around the orders office of Chunkibix Ltd by Cannon's Mr Price-Hargreaves.

That is until Bloome is accused of chasing a young girl across Wandsworth Common, thus making him the hero of every woman in the office. So glorious is Bloome's resultant transformation that when the girl discovers she identified the wrong man he is determined to keep her quiet.

"What we liked was that we were allowed to ad-lib," quips the comic, who turned 70 last month. "I just love the fact every night is slightly different - no two shows are the same. It did, however, make things hard for the other cast members, who just had to sit there and take it. But they've become used to us now."

Indeed, about one half of the play is entirely unscripted. "This means that, overall, it's a lot more fluid, more flexible," he adds. "Yeah, I prefer to do ad-lib instead of reading lines off a script."

Moving on to his career in general, Tommy tells me of the moment he and Bobby Ball first met in the early 1960s: "We were both welders in the same factory, and Bobby was the first person to speak to me on the shop floor. He just came up to me and asked me if I wanted to go to the pub with him after work.

"Later on, he asked me if I wanted to start a double act and I felt that I had nothing to lose, so why not?"

Fast beginnings greeted two of Britain's biggest TV stars during the 1980s, with an annual TV series and Christmas specials, as well as their own feature film, Boys In Blue.

Their 1988 season at the London Palladium broke all box-office records, and the pair have countless fans here and in America.

"It was great meeting all these famous rock stars and actors who would come up to us and say that they were great fans and calling us their heroes," Tommy recounts.

I'm keen to discover the success of Cannon and Ball's 43-year career, but when asked the secret of their success Tommy is as curious as I am. "You need a magic ingredient, which you either have or you don't have. I don't know what it is, but if I ever find out... let me tell you, I'll get you and one of your mates, stick you together and make a double act. We'll be rich!"

However, even after all these years Tommy says there's "nothing better" than performing alongside his partner.

"We'll never retire. We don't really need to keep working nowadays, but we do it just because we love performing. You'll see us soon, coming out on stage in our Zimmer frames, but still performing!"

Who knew that one of Britain's greatest comedy double acts would have met in a welding factory? Their chemistry on stage and screen is so utterly natural, so perfectly timed, you'd be forgiven for thinking Tommy Cannon and Bobby Ball have been comedians since birth.

Bobby Ball, real name Robert Harper, admits he's always had a penchant for the stage. "I had a fantastic family life growing up, very loving. I used to sing in clubs with me mum and dad", the 64 year old comedian tells me in his characteristically thick Northern drawl. "Did singing in all the local clubs, sometimes with me sister. Yeah, it was a very loving family."

But entertainment wasn't the path he set out on, and instead he worked at the local welding factory in Oldham, where he grew up. That would prove to be the fateful meeting place with fellow funnyman Tommy Cannon. "I first met him at the clocking in gate." After inviting Tommy to come and see him sing at the working men's club, the two friends became a duet, but was comedy on the cards? "Nah, we were just mates, you know, no not at all. But when we started it were fantastic. It's sorta something we just bumbled into."

After struggling through the comedy circuit, performing at working men's clubs up and down the country for a number of years, Cannon and Ball were finally given their own television programme, The Cannon and Ball Show in 1980. It was so popular it ran for another 12 years.

But Bobby realised that he had "made it" only when he and Tommy appeared on This Is Your Life in 1980. "We were walking out having just done On Top of the Bill in Blackpool, and there were these huge crowds of people queueing up. We thought what they all standing out in the cold for?' The queue went on for half a mile, we thought it were a queue for summat else, not for us. When we saw that red folder... oh, it were unbelievable."

Their credentials are impressive: their career has spanned more than 40 years including television, feature films and countless theatre and panto appearances. The pair are now carrying on their success with Big Bad Mouse, which sees Bobby's character, Mr Bloome, unwittingly become the object of every woman's desires. A reflection on the man himself, perhaps?

"Now I'm not being funny here, but I've been told that I'm very much like Tom Cruise - I can't help it, I have to fend em off with a stick. Don't tell the wife!"

Bobby must hope that he'll attract some more admirers with the performance at Windsor, the last in the run of the play, assuring me he's "saved the best till last!"

The man is a bundle of energy - indeed it's hard to keep up with him as he blasts jokes at me left and right, but underneath his rough and ready exterior lies a devout Christian and family man who cares deeply for his wife Yvonne and their three children. The family now live in the peaceful seaside town of Lytham St Annes, Lancashire.

He continues: "You know where I am at the moment? I'm waiting in my car at the train station, picking me kids up coming back from Vietnam. That's what I do as a family man - look after the kids. That is, when I'm not too busy being a sex object."

So will Cannon and Ball ever retire?

"I can't retire," he says. "I already told you, as a sex object I get people following me, stalking me. There'd be women crying all over the world if I retired!"

I try to clarify things: so... it's not that you don't want to retire, it's that you can't?

"You got it in one!" he replies with his infectious laugh.

Big Bad Mouse runs from Monday, July 28 to Saturday, August 2 at Theatre Royal Windsor. Details: 01753 853888