Sir Michael Parkinson can remember the precise moment when he first encountered th world of showbusiness. He was a Humphrey Bogart-fixated reporter on the South Yorkshire Times, with a trench-coat, a drop-handled Raleigh, and a snap-brim fedora with a card reading "Press" in the hatband: the hat was secured with knicker elastic to stop it blowing off in the wind. He wrote, he says, wedding reports in the style of Ernest Hemingway, and theatre reviews in the manner of Dorothy Parker.

He dreamed of interviewing film stars, but Bob Hope and Gene Kelly weren't in the habit of visiting Barnsley. Then, one day, the teenage Parkinson was cycling around the pit village collecting daily news when he noticed a bill for an act called Denis and Sylvana, who were appearing at the working men's club.

"To me, this was cabaret time. I started talking to them, and of course they were desperate, really. They weren't even end-of-the-pier - it had gone beyond that. But I thought these were incredibly glamorous people."

Denis was a dark, slim man, in heavy make-up. Sylvana was blonde and plump. "But to me she was a bit like Bette Davis - kind of tragic." Entranced, he invited them to his parents' house for Sunday lunch. "And my father, faced with a man wearing mascara and rouge, eating Yorkshire pudding well, it did test his simple nature!"

Much has changed since then, but much remains the same. Parkinson fashioned a career from his fixation with showbusiness, and over 36 years on a talk show which defined the genre, met many of the fantasy figures who had illuminated his childhood imagination. He sparred with Muhammad Ali and flirted with Lauren Bacall, and introduced the British public to the wit of Billy Connolly, who ingratiated himself by telling a joke about a man who was using his dead wife's bottom as a bicycle stand. There was a fight with Rod Hull's Emu, a freeze-out with Meg Ryan and Peter Sellers dressed as a Nazi. All that ended on December 27, 2007, when Parkinson was put out to grass by ITV, having previously been revived, then undermined, by the BBC. (Parkinson shows no rancour towards ITV, but is less forgiving about the BBC).

When I meet him in his grand office outside Windsor, he is dressed casually, in a navy V-neck, tracksuit bottoms and snow-white Reebooks, and fussing over a misplaced iPod. With his autobiography on the shelves, his website launched and a job as the government's "Dignity Ambassador" - studying the care of the elderly - to look forward to, he is ebullient. In 1998, he had raged about the decline of the talk show, and the disastrous influence of American hosts such as David Letterman. Last Friday, as a guest of Jonathan Ross, he offered Ross the small compliment: "You're actually a very good interviewer, when you want to be."

Parkinson's skill was humbleness. He liked his guests, was interested in them and listened to what they said. His interviews followed a clear pattern. He always asked about childhood, because he believes it is "the key to everybody".

"I grew up believing that the world was a very happy, nice place, 'cause my parents were very nice people. In working class pit villages there was a bit of drunkenness, some violence, but I was protected from all that - my dad didn't drink, my mother was a determined matriarch.

"I saw it in what happened to some of my friends' mums - I'd see the black eyes, but I didn't really know what had happened. So I grew up with that attitude - just drift along."

He says his father, Jack, was a simple man. "He thought that God was an umpire, and played cricket. He had this very simple attitude to life, which was that everyone he met was nice, and would like him, and he would like them."

His mother, Freda, was "an ambitious woman thwarted by the education system. She left school at 14 when she should have gone to higher education. She was an incredibly bright woman."

She introduced him to writing, filled the house with books, taught him to type and took him to the pictures four or five times a week. "She was my guiding light."

"I grew up being more like my mother than my father. I hope I've now become more like my father than my mother, in the sense that I'm in a more tranquil part of my life. My father was not an ambitious man at all. He didn't understand the meaning of the word."

Parkinson is 73, and if he's not quite ready for the knacker's yard, he seems relieved to have come to an accommodation with the matter of ambition. "Sometimes with ambition - I don't think it happened to me - maybe you become a person you wouldn't like very much. You're persuaded that the way to do it is to blow people out of the way. To be a bugger, if you like."

He has been happily married to Mary for nearly 50 years; they have three sons and live in Berkshire. His interest in the care of the elderly, meanwhile, was sparked by the treatment his mother received in the last two years of her life. "My mum for 94 years of her life was bright, alert, opinionated, and to see that decline was very sad.

"It did give me an insight into a modern-day problem. Any son or daughter who has seen their parents go that way must worry about themselves. Might that happen to me? And if it did happen to me I'd want to be treated a bit better than my mother was, on occasions.

"It was very sad, and it makes you feel like a neglectful child, no matter how close you've been."

But that is a conversation for another day. The book is more of a celebration of the values Parkinson took from his parents. He remains, proudly, a product of his environment.

"I always thought I would marry Ingrid Bergman and we'd live next to Barnsley Football Club. And they'd invite Ingrid up to Barnsley to test her out.

"But I think the movies gave me a different window on the world. My granddad, my father's father, only ever left the pit village he lived in twice in his life. Once to go to Blackpool, once to go to Leeds to a test match. Think about how closed all that was. I hadn't been in an aeroplane until I joined the Army, but my view of America was that it was wonderful: New York particularly. I knew the skyline of New York before I knew the skyline of London or Birmingham or Manchester. And it seemed to be everything that my life wasn't. It was full of extraordinary, glamorous people.

"I don't know where this came from, but I did have a great fondness for American writers from a very early age. My mother introduced me to Scott Fitzgerald and from that point on - apart from my great passion for Graham Greene and Evelyn Waugh - all the rest are Yanks. I read everything that Hemingway ever wrote, or Steinbeck, or John Dos Passos. It just seemed to me they were different, more exciting, than the life I had there in the pit village. It wasn't a longing to be part of it: I fed off the glamour. I had a fantasy life based on that."

Clearly, he still does. Except that sometimes, he gets to step inside the fantasy and live it for a while. Ingrid Bergman may not have come to Barnsley, but Parky, on occasion, went to Hollywood.

An evening with Michael Parkinson, in association with Highland Park, will take place on Monday, October 20, at Glasgow Royal Concert Hall.

The event begins at 7pm (doors open 6.30pm). To reserve tickets call 0141 353 8000. Tickets cost 12 per person (plus 50p card booking fee).