TWENTY years ago the Waltons said "good night" for the last time. The lights in their house in the Blue Ridge mountains of Virginia dimmed for good as the sentimental series came to an end. Now the Walton children are being reunited by Tyne Tees Television for a special After They Were Famous documentary. This follows a similar reunion programme bringing together again the people who played the Von Trapp children in the movie musical The Sound Of Music.

The show, which followed them on a return trip to Austria and recollecting their time making the film, did well ratings-wise despite being scheduled against a big televised soccer match. It's being repeated in the countdown to Christmas by public demand.

The New Year will bring The Waltons reunion, the first time they've all been together since 1982, when the series ended after 12 years on air. Afterwards, three special TV movies were made continuing the story but the cast have long since gone their separate ways.

"I grew up with The Waltons. It started running in this country in 1973 when I was 11. I loved it - until punk happened," says producer-director Mark Murray, who organised the reunion. "Getting them all together again was amazing - they really spark when they're together. They are a real family.

"They're all in touch with each other although David Harper, who played Jim-Bob, is the black sheep Walton. He's a bit of recluse and has had various jobs. Sometimes he's hard to track down. But they are all remarkably well-balanced. There are no scandals. Mary McDonough, who was Erin, jokes, 'none of us have robbed convenience stores'. She says that's because they instantly gelled together from the start." That beginning happened before The Waltons was born. The 1963 film Spencer's Mountain, starring Henry Fonda and Maureen O'Hara, was the forerunner of the series. Like the TV version, it was based on the life of Earl Hamner Jr. His book provided the basis for the story of a poor quarry worker and his family of nine living in rural America in the 1930s.

The film did not please everyone. Critic Judith Crist commented that it was "outstanding for its smirking sexuality, its glorification of the vulgar, its patronising tone, its mealy-mouthed piety".

Her opinion didn't stop a feature-length pilot of a TV series being made in 1971. The Homecoming, being repeated on Channel 4 tomorrow, featured Patricia Neal as Olivia Walton and Andrew Duggas as John Walton.

They were replaced by Michael Learned and Ralph Waite when the series followed in 1974. But the youngsters playing their children - Richard Thomas (John Boy), Judy Norton (Mary Ellen), Mary McDonough (Erin), Jon Walmsley (Jason), David Harper (Jim Bob), Eric Scott (Ben) and Kami Cotler (Elizabeth) - continued in their roles. Will Geer took over as Grandpa, with Ellen Corby staying put as Grandma.

The admittedly-sentimental series followed the family fortunes through the Depression to the Second World War. The Waltons, as someone succinctly summed up, "shunned sex and violence for human tragedy and family drama". As such, it was easy to mock them and the goodnight ending was constantly sent up, but the series became compulsive viewing for millions and re-runs still draw large audiences.

Not all the actors stayed until the bitter end. Olivia disappeared to a tuberculosis sanatorium when the actress playing her wanted out. John Boy - modelled on Hamner himself - went off into the big wide world to pursue his writing ambitions when Richard Thomas grew tired of life on the mountain towards the end of the run. But the six other children never got around to leaving home, although Mary Ellen did become a nurse and marry a doctor who died (allegedly) at Pearl Harbour.

"John Boy was the oldest and there were the six younger Waltons. They say they were always known as 'the kids'. I think that stopped them going off the rails. They were a cohesive family unit. It was an ensemble show and they were not put on a pedestal. They were just a group," says Murray.

Unlike many other American child actors, they didn't take to drink, drugs and a rock'n'roll lifestyle once TV fame ended. Some even continued acting. Judy Norton, a single parent of a six-year-old, still acts and travelled from Canada for the reunion. Mary McDonough has just directed her first short film with the two actresses who played Olivia Walton - Patricia Neal and Michael Learned.

The youngest Walton, Kami Colter, who spent her childhood on the programme, had different ideas. "She's one of the most together and organised people I have met," says Murray. "She knew at 16 she didn't want to be an actor and became a schoolteacher. She put all the money she'd earned behind her, bought a 1957 Ford Thunderbird and went off to college. Now the car's a classic worth $35,000." The pupils she teaches are usually aware of her TV past. "First of all she's Elizabeth from The Waltons but after two days they're regarding her as just a teacher," he says.

Murray took the Waltons back to their old home, which isn't actually in Virginia but on the backlot of Warner Studio in Burbank, Los Angeles. The house is still there, used for other films from time to time. He also arranged for them to attend a Waltons convention being held in Virginia, although Jim Bob went AWOL and missed the event. What would Pa Walton have said?

l The Homecoming is on Channel 4 on Sunday at 3.40pm. The Sound Of Music Children: After They Were Famous is on ITV on Friday at 9.30pm. The Waltons: After They Were Famous will be shown on ITV in the New Year.