A few years ago, the green-fingered, outdoors-loving public rose up when 50/50 was under threat. There were rumours it was going off air owing to sponsorship issues - or was it pressure from industrialists?

Intense lobbying by viewers saw it kept on air, and 50/50 has now celebrated 20 years since its inception.

Although SABC3 and M-Net have been airing superb international environmental documentaries - and there are often better options on Discovery and BBC Prime on DStv - this local TV institution can hold its own.

Amazingly, it's the second oldest environmental programme in the world after Canada's CBC show, The Nature of Things.

Their 20th birthday event in Pretoria was attended by past and present hosts, and Gauteng's environmental boss, Mary Metcalfe.

50/50's intention has always been to deliver engaging material - and, corny as it may sound, it has often been the voice of creatures that cannot speak for themselves.

Producer Danie van der Walt feels the biggest success of the show has been to influence policy and stir the public. "Viewers have often joined the fight to protect our natural areas," he said.

50/50 started in 1984 as the brainchild of Professor Attie Gerber and Van der Walt. At first it aired bi-weekly but in 1986 it became a weekly bilingual show.

Over the years many different presenters worked on it, including stars like Sybil Coetzee, Muriel Dube (Semaka), Jonathan Rands, Esta Terblanche (currently on All My Children), Hlomla Dandala, Erald Felix and Karl Kikillus.

Van der Walt recollects how difficult things were in "the old South Africa, especially when TV was new, but the country was isolated. Attie and I wanted to tell the truth, but it was difficult to get programmes passed. All we were trying to do was to be honest journos, but instead we made a few environmental enemies".

In 1999, 50/50's fate again hung in the balance when the SABC considered dropping the show - until thousands objected.

The same year the show was rescheduled, but there was an outcry over its new viewing time. Ratings dropped from 1.5 million to 300 000. It was restored to its old slot and figures climbed.