The writer and teacher Katharine Moore, who has died aged 103, was asked by her doctor not long ago if her carer was "good with old people". "She doesn't know any," was the firm reply. Old age was a state for which Moore became something of an advocate, especially after she published Summer At The Haven, at the age of 85 - and received the Authors' Club Silver Quill Award for the most promising first novel of 1984.
Unlike the work of other literary latecomers, such as Mary Wesley, Moore's novel dealt with the time of life she herself was experiencing; she took an old people's home as its setting and an old lady as its central character.
This shift of focus from the traditional concern with youth, or even middle age, to the unacknowledged fears, pleasures and trials of old age, which she was to pursue in two further successful novels, The Lotus House and Moving House (1984 and 1986), earned her an enthusiastic reception from critics, who compared her with Mrs Gaskell, and a devoted following among readers of all ages, some of whom corresponded with her for the rest of her life.
Moore was already remarkable for a 22-year pen friendship with the actor, comedian and raconteur Joyce Grenfell, which ended only with Joyce's death, after which their letters were published as An Invisible Friendship (1981). Their agreement never to meet, in order to express themselves with greater freedom in their writing, resulted in an unusually satisfying exchange of ideas, the record of an extraordinary companionship of minds, particularly in spiritual and religious aspects.
Moore's early relationship with religion is neatly summarised in her memoir, Queen Victoria Is Very Ill (1988). "God and Jesus . . . roughly corresponded to my father and mother. God and my father were all-powerful and all-knowing: they gave orders and had to be obeyed; sometimes they shouted. My father could not shout so loudly as God when it thundered, but he had a good try. Jesus and my mother never shouted, and they loved me whatever I did, though they too liked to be obeyed."
The rigorous, bullying Presbyterian faith of her father was difficult for Moore to come to terms with, and it was only the approach to Quakerism in her 30s that reconciled her to belief in a gentler, compassionate God. Her first published adult work was an anthology, The Spirit Of Tolerance (1964).
If her upbringing was, in religious matters, a battle of wills between her father and herself, in another way Moore was singularly fortunate for her time - and, for instance, gratefully acknowledged her father's broadminded attitude towards her education. The family home was in Reigate, Surrey, from where her father commuted to London to his work in insurance, but Katharine was sent to Wycombe Abbey school. From there, her father encouraged her to gain a place at Oxford, in the first exhilarating period of women's acceptance as full members of the university.
From 1918-21, she had three blissful years at Lady Margaret Hall, inspired by teachers such as Janet Spens, the Elizabethan scholar, Walter Raleigh, first Oxford professor of English literature, and Gilbert Murray, regius professor of Greek.
Moore's English degree equipped her for her careers as a teacher and writer; her contacts influenced her recognition of women's need for independence. The titles and subjects of her non-fiction books, written much later, reflect her preoccupation with this important theme of her own life, as well as her religious development - Cordial Relations: The Maiden Aunt In Fact And Fiction (1966); Victorian Wives (1974); and She For God: Aspects Of Women And Christianity (1978).
A short interlude after university, working in the Lady Margaret Hall Settlement in Lambeth, was an eyeopener about poverty to a middle-class girl. While providing a complete contrast to her Oxford years, the experience worked upon a mind by then prepared to receive and absorb new impressions.
Very shortly afterwards, however, Moore's time was to be fully taken up by different responsibilities. In 1922, she married Dr Harold Moore, a widower with three young girls, and soon she, herself, had twins, Jane and Christopher, for whom she wrote her first children's book, Moog, in 1936. Her marriage was very happy, her husband - later a CBE and the first president of the Institution of Metallurgists - continuing the supportive tradition of men in her family.
Accordingly, in 1943, she took up a part-time post as English teacher at Walthamstow Hall school for girls, in Sevenoaks, Kent. The area was heavily bombed during the second world war, and her description of teaching under fire made gripping reading in her war diary, A Family Life (1989).
When the bombs stopped, Moore continued, full-time now and for many years to come, an inspiration in her turn to generations of pupils. Her educational books - Kipling And The White Man's Burden; Richard Baxter: Toleration And Tyranny; Family Fortunes, A Story Of Social Change and Women Past-into-Present - reflected her style of teaching in their entertaining and informed lucidity, and her children's book, The Little Stolen Sweep (1977), showed her ability to appeal to the minds and hearts of the young.
When her son Christopher, then 23, was drowned in a holiday accident, Moore spoke of the terrible loss as dividing her life in two. But she strove for, and ultimately attained, the goal of turning suffering to good account, gaining a depth of understanding of other people's tragedies. Again, following her husband's death in 1972, she refused to succumb to the inertia of grief, and achieved, instead, the late-flowering of her writing talent.
After her three full-length novels, she produced a witty and humane collection of short stories, Six Gentle Criminals, and a fascinating exercise in historical recreation, A Particular Glory, the fictional biography of Damaris, daughter of John Wesley's friend and mentor Vincent Perronet, vicar of Shoreham, Kent, where Moore lived.
"I never had much time for old people," she said in her later years, "so, perhaps, this long life is God teaching me a lesson." If so, it was a lesson that benefited everyone who knew her. Moore is survived by her daughter, and her adopted son, Matthew.
· Una Katharine Moore, writer and teacher, born April 25 1898; died November 18 2001
