John Grierson, the father of the British documentary, said that every cinéaste could learn from Peter Hopkinson’s “great sense of independence and justice”. Hopkinson saw first-hand the birth of the documentary, the medium Grierson had called “the creative treatment of actuality”. He strove to make the creative input one of empathy and impact, although, seeing the world through a staunchly left-wing lens, he believed that reportage should naturally suggest a more equitable world.

Born in Ealing in 1920, Hopkinson had an early love of cinema. He went straight from Lower School at Harrow to the film studios to work as a clapper boy, and then as a camera assistant at Alexander Korda’s studios at Denham. When war came he joined the Army Film Unit under David MacDonald, and was sent to Greece in 1944 to record the British advance. He soon faced the most exciting – and disappointing – episode of his career.

He had attached himself to a commando unit that pursued the Wehrmacht to an airfield at Megara, near Athens, where the Germans made a stand. “Advancing down on our little handful was the rearguard of nothing less than the entire German Army Group in the Balkans,” he later wrote. “The uniform I wore, and not the view-finder of my camera, dictated my actions.” British paratroops began to drop from the sky but many were blown along the ground or into the sea by strong winds, while their equipment was scattered. Hopkinson frantically drove a Jeep around to help to recover the men and munitions. The experience taught him two lessons: never to drive again (he was injured in a Jeep crash shortly after this episode) and never to return to studio production.

Hopkinson made his mark at the end of the war, when the UN Relief and Rehabilitation Association sent him to the devastated Soviet provinces of Belorussia and Ukraine. There he filmed the plight of thousands of orphaned children. The March of Time, the US newsreel service, ran his film with the title The Russians Nobody Knows, and Hopkinson was offered a job as director-reporter.

To have a film deemed worthy of The March of Time, which spent about $50,000 on each report, was flattering, and Hopkinson had long admired the Time Inc newsreels for their focus on refugees and their attempts to show the truth about Nazism when most wanted to appease and oblige. He reported from Asia and the Middle East, showing vividly the tribulations of India before and after independence, and made a prize-winning film on the Suez Canal. By 1951, however, most of America had television, and The March of Time – its doomladen voiceovers much parodied since – came to an end.

For the Council of Europe he made a film on Britain in the Sixties; something he would later augment with A Quality of Life, which traced Britain from the 1930s to the Beat generation, winning the British Film Institute award in 1986 for archival achievement. His film African Awakening, portraying the end of colonial rule in Ghana, Nigeria and Sierra Leone, won Unesco’s Kalinga Prize. Its scenes were, like all of Hopkinson’s work, neither staged nor contrived but infused with a sense of justice and optimism. Hopkinson worked for a while in Malaysia, where he established the film unit Pengarusam Perfilum. Margaret, who was to become his second wife in 1967, managed the continuity. She was to follow him to Kenya, India, Iran and Venezuela to work on the Unesco series A Matter of Families, which sensitively presented the challenge of population control.

One of the most rewarding episodes of Hopkinson’s life was the return to Russia just before the end of the Soviet Union to seek out the orphans he had filmed 45 years earlier. The Orphans of Minsk was shown as part of Channel 4’s Soviet Spring season in 1990.

Having traced the growth of documentary from the days of studio-staged vignettes showing what might have happened to the voxpop style of the modern era, Hopkinson was fascinated by the idea of documentary truth. He was always aware that the medium was vulnerable to manipulation, and in 1995 he gave the National Film and Television Archive’s Ernest Lindgren Memorial Lecture, Uses and Abuses of Archive Film.

In the 1990s the Hopkinsons became reliant on the Cinema & Television Benevolent Fund, moving to the charity’s estate at Glebelands in Berkshire. His book, Split Focus: an Involvement in Two Decades, remains a useful and entertaining introduction to documentary. A second work, The Screen of Change, found a publisher just before Hopkinson’s death.

He is survived by his wife, Margaret, and by two stepsons.

— Peter Hopkinson, documentary film-maker, was born on June 27, 1920. He died on June 28, 2007, aged 87