Born in 1907, the daughter of an officer serving in the Indian army, my mother spent her first seven years in India.

After the first world war the family returned to England and settled in Swanage, Dorset. It was here at the age of 20 that she set up her first studio, having studied photography at the Regent Street Polytechnic.

In 1932 she met Lettice Ramsey, the widow of the brilliant Cambridge mathematician and philosopher Frank Ramsey, and the pair soon decided to set up a second studio in Cambridge.

Helen was thrown into the society of brilliant minds and passionate causes. They photographed many of Lettice’s friends — eminent scientists, writers and members of the Bloomsbury group, many of whom were active in left-wing politics.

It was the time of the hunger marches, the rise of Hitler in Germany and, later, the Spanish civil war. The photograph taken by Lettice of the poet John Cornford who was killed in Spain and his partner Ray Peters became an iconic image for that struggle. So too were the pictures taken by Helen of refugee Basque children arriving by boat in Southampton on the Habana in May 1937.

Lettice and Helen were also captivated by recent developments in photography, in particular the work of Man Ray, and his technique of solarisation or partial exposure, whereby the film is suddenly exposed to light during the development process.

The resulting image gives an ambiguous effect of positive and negative, enhanced by dark outlines. The pair also explored rayograph and multiple exposure techniques and their experimental work behind the camera and in the darkroom produced extraordinary images for which they have since become famous.

Helen also demonstrated much talent as a documentary photographer. In 1937 she went to the Soviet Union with a group of architects, visiting Leningrad and Moscow and then travelling down the Volga in a steamer to Stalingrad.

She took photographs everywhere, mainly of ordinary Russians in markets, women working on collective farms and children in creches. The pictures were made into filmstrip, which Helen later presented in countless Workers Education Association classes and women’s institutes.

A second important documentary assignment took her to the devastated valleys of south Wales, where she photographed the derelict steelworks, ex-miners picking coal off the snow-covered slag heaps and groups of unemployed miners standing about on street corners.

She was deeply affected by both trips and on her return from Russia decided to join the Communist Party. 1937 was also the year that she married my father Jack Dunman, who was working in the industrial department at CP headquarters in King Street in London with a particular responsibility for agricultural matters.

They made a joint decision that she should be the main breadwinner and she set up a third studio in Oxford where she would concentrate on portraiture while he continued with his poorly paid job in London.

She continued to work while bringing up three children. Our family lived in the village of Harwell and after the war Jack twice stood for Parliament as a Communist Party candidate. Helen kept her politics and business firmly apart and became well established, photographing many Oxford academics, undergraduates on degree days and Cowley workers and families in their own homes. Weddings were also a staple source of income.

Recognition came late for Lettice and Helen — too late for the former, who died in 1986. That year Helen was featured in the book Women Photographers: The Other Observers 1900-1950 by Val Williams, which was accompanied by a major exhibition at the National Museum of Film and Photography in Bradford.

She also appeared in a television series for Channel 4, Five Women Photographers, a half-hour film devoted to her, and a further film was made about her in the BBC series Women of Our Century.

At the time, there was a lot of interest in feminism and when Helen was asked how she managed to combine a full career running a business with having a family and political activity, in her characteristic way she shrugged her shoulders and simply said: “I just got on with it.”

Although deeply disturbed by the revelations about Stalin and events in Hungary and Czechoslovakia, Helen remained a party member and never deviated from her socialist principles.

After 1968 she threw her energies into the Campaign for Nuclear Disarmament and opposition to the Vietnam war. After closing the studio in 1977 she returned to live in the family house in Swanage but also had an annexe at our home in Hebden Bridge in Yorkshire. She died in 2001 aged 94 in the knowledge that her work had finally been recognised.

The exhibition at Pallant House Gallery offers an opportunity to revisit Helen’s contribution to portrait photography and reflect on her remarkable life.

• The exhibition Helen Muspratt: Photographer runs in the De’Longhi Print Room at Pallant House Gallery, Chichester, from March 9-May 8, details: pallant.org.uk. Face: Shape and Angle by Jessica Sutcliffe is published by Manchester University Press and can be bought through the Pallant Bookshop, price £30, pallantbookshop.com