The elderly man on the phone was desperate for advice... His ­beloved dog had not been ­himself and was off his food.

Peter Davison listened ­sympathetically but the actor hadn’t a clue what to do.

It is 26 years since he played roguish young vet Tristan Farnon in the hugely popular series All Creatures Great and Small but people still think he can help.

This was not the first medical call he received and it won’t be the last. Peter, 65, said: “People still think we’re vets. Sometimes I do even offer advice.”

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Christopher Timothy, 75, who starred as vet James Herriot in the series which ­attracted 18 million viewers, has had similar experiences.

He recalled: “A woman in the street asked me to come around and look at her cat. I said I wasn’t qualified and she thought I was being really difficult.”

Last night the show’s cast were to be reunited for the first time in decades to celebrate the centenary of Herriot’s birth. The vet’s real name was Alf Wight.

The BBC adaptation of his humorous memoirs of life in Yorkshire, including All Creatures Great and Small and It Shouldn’t Happen to a Vet, made Peter and Christopher, as well as Robert Hardy, now 90, and Carol Drinkwater, famous.

It has been years since they were ­tackling the Dales’ muddy fields, angry animals and eccentric farmers but the memories are still fresh and, for Christopher, painful.

He said: “A cat called Boris was ­infamous in the books. The cat who played him in the show used to get very stressed. One day it bit my finger.

“I’ve never known pain like it. I said the f-word. Fortunately an actress’s head was in the way when I said it and they were able to lose it.”

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Playing James, Christopher also got to grips with piglets in 1988 and, bizarrely, a blow-up doll the following year.

But perhaps his best-loved and most regular client was posh Mrs Pumphrey and her over-pampered pekinese pooch Tricki-Woo.

Peter, who was also the fifth Doctor Who, had an even more agonising ­experience. He said: “You were up to your ankles in cow poo, stomping across muddy fields. You had to put your arm up a cow without the aid of a rubber glove as it was the 30s and they didn’t ­appear until after the war.

“And even though we filmed in the summer months, the tops in Yorkshire could still get pretty cold.

“One time, I stuck my fingers in a cup of hot coffee because it was the only way to get the circulation back.”

But the star, raised in South London and Surrey, still can’t believe how he ­landed the role.

He said: “Before I got the job the closest I’d come to farm animals was being chased by a pig in a farmyard.

“I thought I was entirely unsuitable. Tristan was meant to be very outgoing, a smoking, drinking, womanising creature and I certainly didn’t drink or smoke.

“I had to smoke Woodbines and spent most of the time spitting out tobacco.”

But the discomforts were a small price to pay as millions of fans fell in love with the scenery and the bond between the cast over the 90 episodes from 1978-90.

Christopher said: “They got the ­chemistry right, they got a group of people together who sparked off each other. That doesn’t always happen.” He joked: “I’ve worked with a lot of animals and a lot of kids. I’ve never worked with an ­animal or a child who I wouldn’t work to work with again. But if you want a list of grown-ups…”

Carol left the show in 1985 and ­appeared in Casualty and Peak Practice. She also became an author, writing for children and adults. Her latest title The Forgotten Summer has just been released.

He place on the vets show was taken by Lynda Bellingham, who died two years ago aged 66. Carol, 68 said: “The four of us worked very well together. There was a great electricity between us.” In All Creatures she played James’s wife Helen, based on Alf Wright’s beloved Joan.

Carol recalled: “The first time I met Joan she plonked a photograph of herself on the table and said, ‘This is what I looked like. I was terrified of her, she was ­formidable. But I think she was rather pleased with my portrayal.” The show was so popular that Carol was recognised in far-flung places. She said: “I was on the Great Wall Of China looking out at this amazing landscape when some people walked past and said, ‘That’s Carol Drinkwater from All Creatures Great and Small.’ I was so astounded.”

Coachloads of tourists would arrive to see filming in North Yorkshire but not all the locals liked the disruption. Christopher said: “We were once filming in Askrigg in Wensleydale. Peter and Robert and I were coming out of Skeldale House (the ­veterinary practice in the show). Suddenly they yelled ‘cut’. A local woman had walked across the shot, going to the store.

“She just turned round and said: ‘I’ve got my bloody life to lead you know’.”

But it was Alf who would be uppermost in the stars’ minds for yesterday’s bash at The Gala Rooms in Leyburn, North Yorks. He was 78 when he died in 1995 but his son Jim, 73, has remained determined to keep his legacy alive.

He kept working at his father’s practice and opened the World of James Herriot visitor attraction in Thirsk.

After retiring, he handed the reins to his former trainee Peter Wright and vet Julian Norton. Channel 5 documentary The Yorkshire Vet follows Julian as he goes about daily life in the practice which inspired Alf’s books.

(Image: Mirrorpix)

Jim said Yorkshire folk had a down-to-earth reaction to his late father’s fame.

He said: “He liked that the local people didn’t make a fuss.

“He wasn’t James Herriot to us, he was always Alf Wight.”

Alf was not closely involved in the TV show but became good friends with Christopher, particularly after the actor was knocked down by a car while making the first series, breaking a leg.

The star had to use a wheelchair ­between scenes for two months but Alf admired the way he dealt with it.

Peter is sure that Alf’s stories and the show inspired many vets to take up the vocation. He said: “I got fan mail from a lot of young women who were planning to become vets. I think we were ­responsible for an ­enormous uptake around Britain, probably all over the world.”

HBO, makers of Game of Thrones, may film a big-budget version of the books with Hugh Laurie and Sarah Jessica Parker.

Jim said: “It would be filmed in Yorkshire.” Christopher and Peter are unlikely to mind ­having other actors taking fans’ medical queries for a change.

New hit TV series is about Herriot's old surgery today

Documentary series The Yorkshire Vet is about the same real practice that ­inspired James Herriot’s wonderful books.

The Channel 5 show, which now has a third series, stars vet Julian Norton, who took over Alf Wright’s son Jim’s position when he retired. James Herriot was Alf’s pen name.

Julian said: “When we started The Yorkshire Vet we never dreamt people would want to watch us but I think there’s great honesty that comes with animals. They don’t follow a script, they may wee all over the floor or escape. Their behaviour is unpredictable.”

Like All Creatures Great And Small, Julian, who wrote Horses, Heifers and Hairy Pigs – The Life of a Yorkshire Vet, has had his fair share of funny ­moments. He recalled a worried woman bringing in her dog with a suspected tummy tumour.

He said: “We cut away the hair around the lump and it turned out to be a Fox’s ­glacier mint.”