Jose Harris, who has died aged 82, was the author of a magnificent biography of William Beveridge that established her as the pre-eminent historian of the British welfare state. In that book, published in 1977, just 14 years after its subject’s death, she blew apart cherished narratives about the architect of the welfare state.

She showed that Beveridge’s vision of a universal insurance-based system was poles apart from the kind of welfare state that Britain actually had in the 1970s, which retained a strong means-tested element. A second edition 20 years later gave an enthralling account of Beveridge’s unusual private life, something that Jose had been prevented by his stepchildren from exploring fully in the first edition.

The tension between private life and public service also shaped the book that confirmed her distinction. In Private Lives, Public Spirit: A Social History of Britain 1870-1914 (1993) she traced a profoundly original picture of British society in a period of fundamental transformation. As with all her work, it revelled in the paradoxes and complexities of the past. Grounded in an unequalled command of the sources, it was also the product of a directing intelligence that makes it something of a classic. It secured her immediate election as a fellow of the British Academy.

Born in Bedford, Jose was the only child of Freda (nee Brown) and Leonard Chambers, an insurance officer. She was educated at the Dame Alice Harpur school in the town, and at Newnham College, Cambridge, where she graduated in history in 1962. She then undertook a PhD on unemployment as a problem in social policy in late Victorian and Edwardian Britain, supervised by Richard Titmuss of the London School of Economics.

After teaching at University College London (1964-66), Jose moved to a research fellowship at Nuffield College, Oxford (1966-69). Her interest in Beveridge, already central to her PhD, was nurtured by the then warden of Nuffield, Norman Chester, whose early career had included service as secretary to the Beveridge committee. She then taught for almost a decade in Titmuss’s department of social administration at LSE. While there she published her first book, Unemployment and Politics (1972), and the biography of Beveridge.

In 1968 she married the legal philosopher James Harris, whose importance in Jose’s intellectual as well as personal life was incalculable. They had met as undergraduates at a Christian retreat. Jose admired the inner strength through which Jim, who had been blind since early childhood, built a distinguished academic career. Jose too had a single-minded determination that belied a physical frailty. “All my life people have tried to stop me doing what I want to do,” she was wont to say; but few succeeded. They were perfectly matched in values, intellectual interests and a shared Christian faith, with Jim’s bonhomie a foil to Jose’s intensity. They had one son, Hugh.

Jim was elected to an Oxford fellowship in 1973 and the couple moved to the leafy north of the city. Jose exchanged gardening tips with an elderly neighbour, Lady O’Malley (the novelist Ann Bridge). Only some time after her neighbour’s death did Jose discover that she was the Mary Sanders who had turned down a proposal of marriage from Beveridge 60 years before. The correspondence between Beveridge and Sanders was one of the new archival finds that enabled Jose to produce the enriched second edition of the biography.

In 1978 Jose left LSE to take up a tutorial fellowship at St Catherine’s College, Oxford; only the second woman fellow. There she was part of a distinguished team of historians, but Jose was never outshone. Her work increasingly explored the interfaces between social and intellectual history. She wrote powerfully for New Society in the 1970s and for the London Review of Books in the 80s and 90s. She sounded a sceptical note about politically inspired manipulations of the past, such as “Victorian values” in the 1980s. Correlli Barnett’s The Audit of War, much in vogue among Thatcherite journalists in that decade, was torn to shreds.

Jose was a daunting but inspirational tutor who made a lifelong impression on her students. Her method was to conduct a viva on the weekly essay, on the premise (rarely if ever true) that the undergraduate was her intellectual peer. She deployed to great advantage the ability to remain silent for as long as it took until her question elicited an answer, and unworthy contributions would be beaten back by the blankest of blank looks. She thought punctuality an overrated virtue, and visiting speakers just getting into their stride a few minutes into an Oxford seminar would be disconcerted to glimpse a slight, dark figure sliding into a seat at the back. She could be relied on to ask, not the first, but always the most searching question. Her real exocets were reserved for senior scholars.

She was promoted to reader in modern history at Oxford in 1990 and professor in 1996, then to a Leverhulme research professorship the following year. This might have seen the climax of her academic life, but the later years of her career were clouded by Jim’s death from cancer in 2004. It took Jose a long time to recover personally from that blow, and she never produced the major last work that many hoped for. She remained, however, an influential mentor to a host of younger scholars.

In retirement she relished the company of her two grandchildren, Isabel and James. She took pleasure in her former students’ careers, but her compliments were rarely straightforward: “I really enjoyed your book. It was so much better than the one I thought you would write.”

Hugh and her grandchildren survive her.

• Jose Ferial Harris, historian, born 23 January 1941; died 13 September 2023