My friend and colleague Richard Brock, who has died aged 86, was a BBC Natural History Unit producer for 35 years, and latterly a guerrilla film-maker trying to make a difference through his own means. He enjoyed sharing his passions about the natural world and our impact on it.

He had a long and successful working relationship with David Attenborough, starting with Eastward with Attenborough (1973). They worked together again on the groundbreaking series Life on Earth (1979), with Richard taking responsibility for the sixth episode and amphibian segment, Invasion of the Land.