There is one notable exception. A Passion for Angling appeared on BBC2 in 1993 and it has sold more than 100,000 copies in book and video. The book reached No5 in the non-fiction best-selling list. Among the countries that have taken the series are Mexico, Hong Kong, New Zealand, Italy and Norway. The Japanese, who obviously saw similarities with their own game shows, liked the first two so much that they have bought the set.
Its success was largely due to Hugh Miles, probably the world's finest wildlife film-maker. He had always wanted to produce the definitive series on fishing. His six-part series showing its pleasures starred two friends, Bob James and Chris Yates, and took five years to make.
"Hugh is a total workaholic who only needs about three hours' sleep a night," says James. "He works on the principle of 'no pain, no gain'." James found the lifestyle difficult, Yates found it impossible. Both recall Miles's perfectionism. Yates, for many years the carp record-holder, tells the story of rising before dawn for two weeks, just so Miles could get the perfect shot of the two trudging through the early-morning mist towards a ruined boathouse, and disturbing a barn owl.
James, a better riser but still not in Miles's league, recalls catching an 11lb 13oz barbel, by any standards an exceptional fish and possibly the largest captured on film. Miles was quite pleased, but wanted James to catch another at the same time the following day so he could get shots from the opposite bank.
Both anglers played themselves and the series made them famous. But five years' filming took their toll. James, a career change forced upon him, took advantage of his new-found fame and did angling roadshows, teaching sessions with youngsters and magazine articles. He now works for the Anglers' Conservation Association, a pollution-fighting body, as its press officer.
He is even looking at a new film series, though he accepts that the success of A Passion for Angling will probably never be repeated. "Hugh has achieved what he wanted to. Anyway, he is so popular that he has work into the next millennium. If there was ever going to be a sequel, it would take place another 20 years down the road, when we had all chilled out from the experience. Now, it would be a folly."
He is quick to deny rumours, fuelled by the News of the World, that he and Yates are now enemies. "We are just both different people. I still talk to him and admire his work, but we live a long way apart now. There's no rift."
Yates, a private man, was happy to return to his family, normality and his small Wiltshire home. A Passion for Angling had perhaps revealed too much of his soul. He had no wish to build on its success, other than to write the book of the series. He has no truck with modern tackle and when manufacturers send him carbon-fibre rods to test, he uses them to hold up his runner beans.
However, Yates is about to astonish everyone with a project that will surprise even those who know him. A film project? Another acting role? Surely not his long-awaited book on Night? Well, it's certainly eccentric. But I'll tell you more next week.