Bloomsbury laid bare: Frances Partridge reveals the truth about her fellow writers

I met Frances Partridge on several occasions during the last decade of her life. Still sprightly and alert in her nineties, she was to be seen regularly at exhibition openings and book launches. In 1995 she attended a party at the Imperial War Museum to mark the publication of my first book, a biography of Vera Brittain. Afterwards, she wrote to say how much she had enjoyed the event, though, as a lifelong pacifist, she admitted that she had been disturbed by the museum's display of tanks and guns.

Five years on from Frances Partridge's death – in February 2004, just a month short of her 104th birthday – Anne Chisholm has produced a worthy tribute to the woman often dubbed "the last survivor of Bloomsbury". In the 1960s, Partridge had begun to be sought out by a growing band of biographers and scholars documenting the lives and work of the Bloomsbury group – a world Partridge had formally entered in the mid-1920s through her relationship with her future husband, Ralph Partridge, and her entanglement in the ménage he shared at the time with his first wife, the artist Dora Carrington, and the writer Lytton Strachey, at their home at Ham Spray on the Berkshire Downs.

Having survived the distinctly unnerving experience of seeing the private lives of herself and her friends dissected in print and exposed in newspapers, on stage and, eventually, in film and on television, Partridge embarked in old age on a new career as a memoirist and diarist. In 1978, she published her first book, A Pacifist's War, a lightly edited version of the diary she had kept during the Second World War. Its glowing reception thrilled her, though she was bewildered by having been pushed, or having "stepped of my own free will – onto the stage in the glare of footlights". In all, six further volumes of her post-war diaries were to appear between 1985 and 2001, distinguished by the honesty, humour and plain curiosity about human nature that were the outstanding qualities of Frances Partridge's writing.

Chisholm's biography is based on the published works, the archive of diaries and letters bequeathed to King's College, Cambridge, as well as conversations with Partridge towards the end of her life. Disappointingly, most of the diaries no longer exist in their original manuscript form; it was Partridge's habit to destroy these originals as she produced the edited typescript that was sent to the printers. Nevertheless, she left behind many traces of the kind of material she had decided not to publish for fear of causing offence or hurt to family and friends, and it is from these that Chisholm has managed to develop, for the most part, a perspective of critical detachment.

Frances Partridge was born into a liberal-minded family with peripheral connections to members of the Bloomsbury Group. Her mother, Margaret, was acquainted with the Strachey family, while her father, William Marshall, was an architect – one of his commissions was a study for Darwin, at his home at Down House, in Kent – and included Leslie Stephen, Virginia Woolf's father, among his friends. Partridge's first significant encounter with the unconventional circle whose lives she was to chronicle came in 1922 when, after graduating from Cambridge, she went to work at the bookshop co-owned by her brother- in-law, Bunny Garnett. Here she became acquainted with Leonard and Virginia Woolf, and sent books out to EM Forster in India, and to Gerald Brenan in Spain. Bloomsbury, with its love of conversation and ideas, and its standards of "courage, independence, passion for the truth and reality instead of romance and hypocrisy", fitted Frances like a glove. By 1923, one of its members, Ralph Partridge, who had worked for the Woolfs at the Hogarth Press, had fallen for her. Clive Bell, who said that Frances had the best legs in Bloomsbury, announced that Ralph was in love with "a black-haired beauty... a beautiful Princess that lives in Birrell and Garnett's bookshop".

At Ham Spray, however, Partridge soon found herself regarded as an interloper. Carrington's marriage to Ralph may have been disintegrating, but Carrington resented Ralph's feelings for his new love, while Strachey regarded Frances as an inconvenient obstacle to his passion for Ralph. Frances Partridge remained characteristically resilient in the face of this difficult situation. In later years, while always championing Ralph, she also managed to avoid direct criticism of either Carrington or Strachey (though she remained resentful, as I discovered, of Strachey's failure to acknowledge adequately the part that she and Ralph had played in helping him to edit the Greville Memoirs, an aspect of their relationship overlooked by Chisholm).

Strachey's death from cancer, in 1932, produced an even more emotionally distressing state of affairs. Carrington became suicidal, and eventually managed to kill herself, while Ralph and Frances were away from home, in a horrifically bungled attempt with a shotgun. Inevitably, Bloomsbury looked

for a villain of the piece, and Frances was believed by some to fit the role. But, after her marriage to Ralph in 1933 and the birth of their only child, Burgo, in 1935, things settled down – despite Ralph's eye for a pretty girl. Ham Spray again became a haven for their circle of friends, especially during the Second World War when Ralph, who had been buried alive in rubble and mud as a soldier on the Somme, registered as a conscientious objector.

Their way of life can seem to have been insulated from reality. Both Partridges had private incomes and never felt pressure to earn money. They always put the needs of friends before family. (Frances didn't attend the funerals of either of her parents.) And, apart from the coolness displayed towards them by certain people in their local village, they encountered little opposition to their pacifist convictions. One of their neighbours, VS Pritchett, portrayed the Partridges in a short story, in which they appear detached from the main concerns of life, busy with their friends while their young son grapples with his demons.

When it came to the upbringing of their son, both Frances and Ralph floundered at times. One visitor to Ham Spray felt sorry for the boy, as his behaviour was always under scrutiny, "as if he were a Freudian case study in child development". (Frances Partridge had compiled the index for the English edition of Freud's Collected Works.) As he grew older, Burgo, not surprisingly, became disillusioned with his parents and their values. "I have been disillusioned since I was 10," he told one friend, while he criticised his mother for taking herself so seriously: "You treat yourself like a sort of cathedral." For their part, Frances and Ralph expressed their disapproval when, on coming down from Oxford, Burgo decided to write a book about orgies. When one considers Bloomsbury's liberal attitude to sex, this appears distinctly odd and not a little hypocritical.

Frances Partridge suffered two terrible blows in quick succession. First the death in 1960, of her beloved Ralph, after several years of poor health. Then, devastatingly, Burgo, recently married and with a baby daughter, died suddenly in 1963, while still in his twenties. Rebuilding her life after these two tragedies required an overwhelming effort, but it was a task Partridge met with extraordinary fortitude. Her diary became the repository for her feelings of loss and grief.

I saw Frances Partridge for the last time in July 2002, visiting her in her flat in Belgravia to present her with a copy of the edition of Strachey's Eminent Victorians for which she had written an introduction. She was frail from a recent fall, but remained mentally vibrant. We sat in her pink sitting-room, with Carrington's famous portrait of Lytton Strachey reading, above the escritoire, and a brightly coloured mosaic of a cat by Boris Anrep, set into the fireplace. Partridge's brown eyes blinked vacantly, and she said that life was hopeless with failing eyesight. But she talked animatedly about the past, as if it was a lifeline to her survival: of how she had liked Vanessa Bell better than Virginia Woolf because of her warmth, and of how she felt that recordings of Virginia's voice gave a misleading impression of its deepness.

As I got up to go, she turned her heavily creased face to me and said, with the irresistible sweetness and charm that had captured so many, "Do telephone if you ever need to ask me anything about Bloomsbury, and please come again."

The extract

Frances Partridge: The biography

By Anne Chisholm (Weidenfeld & Nicolson £25)

"...When Frances began to fall in love with Ralph in the summer of 1923, the bookshop network would have ensured that she knew his marriage was unusually stormy and that he and his wife shared a house in the country with Lytton Strachey..."