The cast members and show's writers gathered at the Imperial War Museum
Ex-Dad's Army star Ian Lavender has attacked broadcasters for failing to make TV programmes for families.
"Sadly everything now is done for demographics," said the 62-year-old, who played Private Pike in the war-time comedy series.
The actor, who recently starred in EastEnders, was speaking at a reunion with surviving cast members to mark the 40th anniversary of the show.
The BBC comedy was first screened on 31 July 1968 and ran until 1977.
"It's rather sad that Dad's Army has to be repeated on TV, although I'm delighted to see it of course," Lavender said.
"But there's a need for it because they're not making programmes for the whole family to watch.
"It's amazing that there are children watching this now whose parents were not born when we started.
"But it's because it's so funny, and all the family can watch it, your sick granny, the kids, everyone.
Dad's Army ran for 80 episodes
"Sadly everything now is done for demographics, whether it's selling a chocolate bar or television."
"I'm not happy with making or selling anything for a particular group. Why cut people out? It's divisive. Why make things that only your children want?" he said.
Lavender was joined at London's Imperial War Museum on Wednesday by Bill Pertwee, 81, who played Warden Hodges, and Clive Dunn, 88, who starred as Lance Corporal Jones.
Also there were Frank Williams, 77, who played the Reverend Farthing and Pamela Cundell, 82, who joined the cast in 1969 as Mrs Fox.
Lavender is one of only five members of the show's main cast who are still alive.
Arthur Lowe, who played Captain Mainwaring, died in 1982, while John Le Mesurier (Sergeant Wilson), died a year later.
A one-off BBC special to commemorate the show's 40th anniversary featuring some of the series' stars, its creators and celebrity fans, will be screened later this summer.