IT STARTED with a smile.

A toothpaste smile, in fact. Sally Reid's acting career, she reveals while displaying her bright, wide smile, began with a tube of dentifrice.

Sally was 10 when she was cast in a TV commercial – by chance. A casting director spotted her and her white-toothed chums hanging out around a street corner in her home town of Perth and thought they would look great in an ad for Signal toothpaste.

"They wanted kids who looked very Scottish and I was cast because I had this goofy-looking red hair," she recalls, grinning.

"I was quite shy at the time, but at the same time I was really curious about the filming."

Sally, who recently starred in new BBC Scotland sitcom pilot Scot Squad, had already revealed hints of thespianism.

As a child she had been captivated by the notion of acting out old Hollywood movies. And after the Signal experience, she made her way to a local youth theatre group.

"It was just for fun," she admits. "I'd had a taste for acting, but when it came to leaving school I still didn't realise acting was a real job for someone Scottish. It was for people who had grown up in Hollywood.

"But the lady who ran the youth theatre was encouraging."

At 17, Sally faced a dilemma: to have a go at acting or study Art History.

"I came to Glasgow to study acting, at Langside College, as a taster. I was too young to get into drama college.

"And I loved it. I reckoned that at the end of my HND I would probably go on to drama school, the RSAMD."

However, Sally's talent propelled her into the deep end.

"At the end of my college year I did a showcase, landed an agent and got offered work."

Straight out of college she worked in Factory Girls, the Frank Lynch play. And she has not really stopped since.

"I got my training on the job," she says. "And in Factory girls my character was bolshie, which helped me to appear more confident."

At 31, Sally is something of a theatre veteran, a class act and a National Theatre of Scotland star whom directors know can be called upon deliver.

In Days Of Wine And Roses, for example, her character spanned the years, from a wide-eyed twentysomething to a 38-year-old alcoholic.

From tonight, she is starring in the Tron panto, in which director/performer Johnny McKnight's Aganeza Scrooge will see all the traditional Dickens characters played entirely trouserless.

The characters in the classic tale will all be magically transformed into girls, all played by females, except for Scrooge, who will be played by Johnny in drag.

Sally plays Tiny Tim, the poor little polio-stricken creature with the crutch. And her Tim will most certainly not be a him.

"I'll play him as a young boy," she says, smiling. "But I've sort of got The Muppets in mind. They were rather asexual (Miss Piggy apart) so the essence of the wee boy will be in there, but we'll refer to the character as 'she' or 'her'.

"But the brilliant thing about panto is that people will buy whatever you give them."

Sally is something of a panto veteran. She has appeared in the Tron panto for the past five years and has previously worked in Forbes Masson's panto at the same venue.

"I have seen the evolution of the Tron pantos and think I understand the Tron style," she says.

"It's post-modern, turn panto on its head, with ironic characters and story and the feeling you are letting the audience in on the joke. Audiences like that.

"Johnny says he wants all of us to show off what we can do. That's why I'm playing Tiny Tim as a Cockney. But so long as it works - and I think it will."

Sally owes panto so much, as she admits. "I went through an acting education with panto. I have not been trained as a singer or a dancer. But I have sort of grown with the notion of telling a story through dance or song."

Sally's comedy talent is unmistakable, producing side-splitting performances in theatre such as Valhalla. But she also reveals great range.

And she takes the craft very seriously. Although often cast as a teenager because she looks young, when she played an alcoholic she studied the psychology of alcoholism.

Sally even studied up on Tiny Tim to understand his condition.

"I read a report from a doctor in Australia who tried to diagnose Tim's condition via the symptoms he displayed. The verdict? Polio. Or perhaps rickets."

She is hoping Scot Squad will run to a series.

"Theatre is great but you still have to pay your rent," she says. "And people don't think you have made it until you appear on the telly.

"Having said that, I love what I do. Next year I will be appearing in Dundee in Time And The Conways, playing an old, spinstressy schoolmistress.'"

Sally smiles as she admits the odd grump.

"At the end of one acting day I said to my mum how tricky it had been to play a difficult teenager.

"But she put me straight. She said, 'Sally, I've worked in the same job with the same people for 30 years.'

"That brought me right back to earth."

l Aganeza Scrooge, Tron Theatre, Today-January 5.