Johnny Byrne was a hugely prolific and successful writer for British television, but the Dublin tenement where he grew up, during the Depression and Second World War, was a thousand miles from the rural backdrops to the popular, feelgood television dramas that made his name. He was the lead writer and, eventually, script consultant on All Creatures Great and Small (1978-90), the long-running series based on James Herriot's semi-autobiographical books about a country vet, and the principal writer on Heartbeat, about a village policeman in North Yorkshire.
All Creatures Great and Small starred Christopher Timothy as James Herriot, the vet who joined Siegfried and Tristan Farnon (Robert Hardy and Peter Davison) in a North Yorkshire practice. Viewers were kept amused by their exploits, dealing with problems from an impotent bull to an exploding cow. In the first episode scripted by Byrne, Herriot met his wife-to-be, Helen Anderson, played by Carol Drinkwater – and the off-screen romance between Timothy and Drinkwater only served to boost audience figures.
The programme's fictional small town of Darrowby was a forerunner to the village of Aidensfield, the setting for Heartbeat, to where Byrne decamped after All Creatures Great and Small had run its course. He was adept at writing scripts with dramatic twists in gentle surroundings, so it was no surprise that in 1992 he was hired as principal writer on Heartbeat, based on Nicholas Rhea's "Constable" novels about a village policemen in the 1960s. He continued with the ratings-topping series until 2005.
Born in Dublin in 1935, the eldest of 13 children, Byrne sailed to Liverpool at the age of 21 where he took a job on the docks, sorting dunnage. He mixed with the port's bohemian community and became involved in the emerging pop culture, organising poetry and jazz sessions that gave opportunities to poets such as Brian Patten and Roger McGough.
Byrne went through a string of jobs, as a Christmas tree-feller, an electrician's mate, a manager for ecclesiastical suppliers, and a teacher of English as a foreign language in London, Paris, Athens and Istanbul. He was also a tour manager for the American record producer Shel Talmy's rock groups, which included The Who and The Kinks, and himself performed as one half of the surreal act the Poisoned Bellows, with the poet Spike Hawkins.
In London, Byrne began writing science-fiction stories for magazines such as Science Fantasy and Impulse. Then, with Jenny Fabian, he wrote the bestselling novel Groupie (1969), whose stories of sex, drugs and rock'n'roll in the Swinging Sixties captured the spirit of the underground culture. "Jenny Fabian and Johnny Byrne have succeeded in showing what life is like in a world where the extraordinary is commonplace and to be commonplace is a sin," wrote Jonathon Green in Rolling Stone.
This led to Byrne's first television script, Season of the Witch (1970), in the celebrated "Wednesday Play" slot, which starred the singer Julie Driscoll as a woman who drops out of the typing pool in an attempt to find herself. Then came the zany Adolf Hitler: my part in his downfall (1972), Byrne, Norman Cohen and Spike Milligan's feature-film version of Milligan's first volume of autobiography, before Byrne returned to science fiction to write episodes of Gerry Anderson's live-action series Space: 1999 (1975-78), of which he was also executive story editor for the first series, and three Doctor Who stories (1981, 1983, 1984).
In the middle of All Creatures Great and Small's run, Byrne became script editor of another BBC veterinarian drama, One by One (based on David Taylor's books and starring Rob Heyland, 1984-87), also writing some episodes. He later created Noah's Ark (1997-98), featuring Anton Rodgers as a country vet, for ITV.
John Christopher Byrne, writer: born Dublin 27 November 1935; married 1975 Sandy Carrington-Mail (three sons); died Norwich 2 April 2008.