English Modernism was graced by five daring and gifted women who were in many respects well in advance of their native male counterparts: Virginia Woolf and Anna Kavan in prose, Edith Sitwell in poetry, Elisabeth Lutyens in music and Barbara Hepworth in sculpture. Barbara Ker-Seymer is not remotely in this class. She took some attractive photo-portraits before the war in her studio above Asprey’s and that was it.

Not that Barbara cared. Though trained at the Chelsea School of Art, she had a deprecating attitude to her activity which was characteristic of English amateurism and is absolutely maddening when it comes to the arts at a proper level. Woolf, Kavan, Sitwell, Lutyens and Hepworth were deadly serious about their vocations. Barbara had no vocation. She’d carried on the photography business of her boss, the woman who’d taken her virginity, Olivia Wyndham, when Olivia flitted off to the USA to lay siege to Edna Thomas (who succumbed).

Barbara was born in 1905 into the gentry, but her father was penniless and he ensured, via gambling, that her mother became penniless too. She grew up in a small house near St Paul’s Girls’ School, which she attended, and was soon drinking, drugging and dancing round town. Her vital friendships were with gay men, especially Edward Burra and Frederick Ashton, and also Afro-Americans visiting London or who she met in New York.

The usual suspects (Nancy Cunard, Cyril Connolly, Evelyn Waugh, the Lehmann sisters, Elizabeth Bowen, Oliver Messel) went up her stairs to be snapped in a cool 1930s style that – despite the urgings of her friend Brian Howard and the claims of her biographer Sarah Knights – never overstepped the mark into cutting-edge. The book’s preambles make much of her links to Jean Cocteau and Man Ray. It turns out that she once photographed Cocteau in Toulon for Town & Country magazine; and Man Ray sent her a saucy postcard, though there’s no evidence they actually met. The moment that war was declared Barbara gave up photography and fled the city for the country. Later she joined a film company. She never enlisted in any defence organisation.

She wasn’t pretty. However, she was on the circuit and frolicsome. She had affairs with both sexes, not in the traditional way (marriage plus a sequence of lovers), but in the free-love parallelism associated with the 1960s. She did marry twice, on doolally impulses, but her husbands were even less satisfactory than her boyfriends and girlfriends. Knights has been assiduous in untangling these liaisons, but the impression Barbara gave to her contemporaries remains: a very messy love life.

After the war she might have gone back to photography – but no. By this time she was a single parent and needed to fund the upbringing of her son. When visiting America she’d seen things called launderettes. She opened several in London and did well. However, when her son was eight, she packed him off to boarding school and had another go at Harlem (it didn’t last long).

When Barbara’s work was reappraised towards the end of her life, she expended much energy avoiding publicity. She claimed to have lost her negatives along the way; but after her death in 1993 they were discovered in her home and given to the Tate. In his Journals, Anthony Powell, a long-time friend, described her as having ‘colossal egotism’. I’m sure Barbara would agree that Powell was fond of accusing others of his own characteristics (in the same volume he described me as being ‘greatly pleased with himself’). She strikes one as a free and generous spirit.

We have had many accounts of the lives of the Bright Young People at the Ritzy end of society. Barbara’s antics were more Lyons Corner House. The book is unusual in that it conveys what it was like to hang out in that era with no particular privileges. It is replete with colourful near-unknowns who were as much a part of the zeitgeist as the bigger names, and perhaps even more determined to bring chrome, zigzags and jazz rhapsody into their lives. This is underpinned by the author’s chatty style of short sentences (what joy to bump into a semicolon on page 42) and simple vocabulary, e.g. ‘Billy always kept a tin of salmon in the cupboard in case Fred turned up for a fish-cake supper.’ Knights refers to her subject as ‘Bar’ throughout, a misjudgment in my view. This faux cosiness buckles wonderfully on page 238 as a true monstre sacré enters the story – Patricia Highsmith – and destroys everything in sight. It says much for Barbara’s big-heartedness that she and Highsmith remained friends.