My friend and former colleague Nigel Evans, who has died aged 71, made more than 40 documentaries championing the rights of disabled and marginalised people. We made our first films together in the late 60s, following a small group of heroin addicts struggling to overcome their addiction. Two years later, we made an Omnibus film for the BBC, Seeds of a New Life, about a drama teacher, Dorothy Heathcote, who worked with disabled people.

In 1973, Nigel was awarded a Churchill scholarship to explore new approaches to working with marginalised communities. He founded the charity One Plus One, which supported volunteers in working with patients in psychiatric hospitals. This began in four hospitals, but by 1978 the number had grown to 21. His film Silent Minority (1981) exposed the neglect and abuse of psychiatric patients.

In 1980, Nigel became a member of the steering committee that launched Channel 4, and in 1982 he worked with Stephen Frears on Walter, the feature film chosen for the channel's opening night. This was followed by Skin Horse, a film essay exploring the emotional and sexual needs of disabled people, which won a Royal Television Society award. Pictures in the Mind (1987) was the first drama-documentary in sign language. In the 1990s, Nigel decided to train as a psychogeriatric social worker.

Born in Guildford, Surrey, to Air Chief Marshal Sir Donald Randell Evans and his wife Pauline (nee Breach), Nigel was educated at Wellington college, Berkshire, and enrolled at the Sorbonne in Paris during the birth of French new wave cinema. Enthused by what was happening in Paris, he returned to England and became part of a group of independent film-makers and producers who were recording real-life stories.

Later in life, he turned to writing, first with The White Headhunter (2003), published under the name Nigel Randell, the story of a 19th-century sailor. This led him to research his next book, Boy From the Sky (2013), in Tonga, where he met his second wife, Cindy. They lived there for 10 years until his illness last year, and married in June this year. She survives him, as do three children, Andrew, Katie and Gaby, from a previous marriage to Donna, which ended in divorce, and a stepson, Dominic.