MY mother – like seemingly all women of a certain age– was a die-hard fan of the Osmonds. So what did she know about Jimmy, the youngest brother?

Her reply said it all: "He's the long-haired lover from Liverpool!"

That was 1972 and still little Jimmy Osmond remains in the memory as the cute, hirsute boy, larking about on the banks of the Mersey.

He is still all perfect American teeth and "Hey, how you doing?" and the truth is he retains a boyish enthusiasm – even though he's now 45 years old.

The youngest of the Osmond clan, Jimmy went into showbusiness when he was three years old. After two whole years of toiling away and paying his dues, finally, at five years old, Jimmy had a gold record with My Little Darling, recorded with his brothers.

In 1972, at nine years eight months, he had his eye on a solo career and had a UK hit with Long Haired Lover from Liverpool. The song went to number one in the charts and Jimmy still holds the record for the youngest person ever to sit at the top of the UK singles chart.

Alongside all the showbusiness stuff, the other interesting thing about the Osmonds and Jimmy in particular, is their religious upbringing. Jimmy is a devout Mormon, interesting in itself, but what makes it particularly relevant is the reason why we're speaking – he's coming to Yorkshire next week to take to the stage, where he will play a drinking, smoking, swearing, sleazy lawyer.

Little Jimmy is playing the part of Billy Flynn, the lawyer in the touring stage production of Chicago.

The musical of fame-hungry women, desperate for celebrity, even while they are locked behind bars for committing crimes, was made into a movie in 2002 with Richard Gere as Flynn, the slimy lawyer who is willing to sell his soul – and those of his clients – for a price.

How does this possibly sit with Jimmy's personal moral code?

"The producers have been great, just great," says Osmond, referring to the fact that he has been allowed to not swear while playing the part. "When you actually watch Chicago, it deals with real issues, that are really happening even now. The whole story is about how people will do anything for celebrity, I think that's a real poignant idea."

Performing, clearly, comes naturally to Jimmy. So does something else – business acumen.

By the time he was 15, he was running the Osmond empire. The band had sold more than 100 million albums and the teenage Jimmy had developed and supervised most of the family's merchandising business.

Soon after, he launched a successful advertising agency that handled campaigns for larger corporations, such as Yamaha and Coca-Cola, as well as an elite portfolio of other high profile clients. Also, during this same time, he starred in his first motion picture entitled The Great Brain, as well as two award- winning episodes of the TV show Fame, and performed his own show to sell-out crowds in Madison Square Garden.

All of this begs an awful lot of questions, but one of which has to be, why on earth is he touring the UK with a stage show, playing a character of dubious morality.

"I'm skint," says Jimmy, before bursting into loud laughter, the very idea something almost unfathomable. "No really. It's funny. I have this weird little idea that I want to live life while I can. What am I gonna do? Just go golfing?"

He laughs again.

"The producers came to me with the idea and I just thought: 'This sounds cool'."

Can anything dampen the puppy-dog spirit of Jimmy?

"Hey, we've had peaks and troughs in our careers, so when you get a chance to do something like this, you just appreciate it.

"Touring around I get to be in a different UK city each week and that's really cool."

Mum will be pleased that, 30-odd years on, the Long Haired Lover From Liverpool is cute and excitable as ever.

Chicago is at York Grand Opera House, April 20 to 25. Tickets on 0844 847 2322.