James Herriot when he was just a young pup

Now in what has been billed as a spiritual prequel to one of the BBC's most beloved dramas, the story of Alf Wight's formative years in pre-war Glasgow is to be told in a primetime series.

Young James will focus on the fledgling career of Mr Wight - better known by his pseudonym James Herriot - during his time at Glasgow Veterinary School in the 1930s.

The three-part drama draws on unpublished diaries and case notes the vet and writer compiled during his upbringing in Scotland's biggest city, and his time spent learning his trade as a locum in Ayrshire.

Kate Croft, the show's producer, told The Scotsman yesterday that she envisaged a "coming of age" story that would appeal to fans of All Creatures Great and Small and younger viewers alike.

Mr Wight's son, Jim, said Young James would "answer all those questions" posed by fans of his father down the years.

The programme, which will be broadcast next year on BBC1, was written by Johnny Byrne, one of the original screenwriters of All Creatures Great and Small, which ran for seven series between 1978 and 1990.

Mr Byrne lost his battle with cancer two years ago at the age of 72, but Ms Croft said it was his "dying passion" to see Young James reach a national audience.

"The show was a labour of love for Johnny. It was his dying passion to see it brought to the screen," she said.

"Johnny knew Alf and was someone who loved animals too. As such a visionary and exciting writer, he had an eye for a great story, and thought Alf's time in Glasgow had a right to be a drama.

"It's a story that hasn't been told before. The Wight family have been fantastic, too, giving us a cornucopia of information from the family attic."

Ms Croft added: "We want the new programme to be half rural, half urban.

"The fact someone like Alf was in the ramshackle, busy life of 1930s Glasgow is a nice contrast. It's his coming of age story, set in a period before antibiotics, when veterinary work was in the dark ages."

While the popular perception of Mr Wight has him as a native Yorkshireman, he was born in Sunderland, before moving to Glasgow's Dumbarton Road with his family aged just three weeks. At the age of eight, he was working delivering milk before dawn for three pence a week, before heading off to Yoker Primary.

His father, who worked in the shipyards and played the piano in silent movie theatres, and his mother, a singer, raised enough money to send their son to veterinary school. However, the young Wight found jobs scarce upon his graduation in 1939, sealing his move south.

"Nobody wanted vets," he later recalled. "My friends had to get jobs in the shipyard."

His son, Jim, who also attended Glasgow Veterinary College and later joined his father's Yorkshire practice, said: "Now we have been able to piece together the never before told stories of his college days, and these stories are equally as fascinating."