Lord Dacre of Glanton

Wide-ranging historian whose error of judgement in authenticating Hitler's diaries brought him unwelcome publicity

Hugh Redwald Trevor-Roper, historian: born Glanton, Northumberland 15 January 1914; Research Fellow, Merton College, Oxford 1937-39, Honorary Fellow 1980-2003; Student, Christ Church, Oxford 1946-47, Censor 1947-52; Regius Professor of Modern History, Oxford University 1957-80; Fellow, Oriel College, Oxford 1957-80, Honorary Fellow 1980-2003; director, Times Newspapers 1974-88; created 1979 Baron Dacre of Glanton; Master, Peterhouse, Cambridge 1980-87; married 1954 Lady Alexandra Howard-Johnston (née Haig, died 1997); died Oxford 26 January 2003.

Hugh Trevor-Roper – Lord Dacre of Glanton – was one of the most wide-ranging British historians of his day. With equal skill and authority he could publish – in the same year, 1964 – editions of Gibbon's Decline and Fall of the Roman Empire and of Hitler's War Directives. Master, in the words of Noel Annan, of "a sinuous graceful ironic prose that descended from Gibbon" (via an early mentor Logan Pearsall Smith), he wrote equally well about Persian stirrups, Scottish witches or the architecture of the Escurial.

The son of a Northumberland GP, Hugh Trevor-Roper had a conventional upbringing, later saying "we were pretty dull children and lived in our enclosed little world". Having studied at Christ Church, Oxford, as an undergraduate, he remained there as a don (he failed to win a Fellowship at All Souls). He did not leave Oxford until 1980, except for an interruption during the Second World War when, like his friend and teacher J.C. Masterman, he served in the Secret Intelligence Service.

He thereby acquired personal experience of bureaucracy's capacity for venomous and wasteful intrigues. Despite his work on decoding German ciphers, he was considered "awkward and independent", and was once tried in camera for "dangerous contacts". He regarded the most dangerous contact of all, his colleague Kim Philby, as subtle and charming but his superior, Stewart Menzies, as "a rather stupid man".

At the end of the war Trevor-Roper advocated dropping the use of traditional agents in the field, whom he described as "of very limited value", indeed often "a serious danger to their employers", in favour of double agents and deception. Trevor-Roper's experience in intelligence, and visits to Germany in 1945 and 1946 while interrogating Nazis – which left him with a lifelong distaste for Germans' "extraordinary docility" in defeat – helped him to write The Last Days of Hitler (1947). It sold over half a million copies, enabled him to buy a Bentley, and has never been out of print.

At the age of 40, he married Lady Alexandra Howard-Johnston, daughter of Earl Haig and a talented musician with a gift for interior decoration. There were no children. Trevor-Roper was thin and donnish in appearance, and walked with a slight stoop. Urbane and fluent on the written page, in conversation, and generally, he had moments of rudeness.

Indeed he enjoyed vendettas as well as friendships. Rival historians were demolished with a mixture of scholarship and vitriol. Among his victims were Laurence Stone (over the Elizabethan aristocracy); R.H. Tawney (for believing in the rise of the gentry); Arnold Toynbee (who dared to have a theory of history); and A.J.P. Taylor (over "that ridiculous book on the origins of the Second World War").

Having lived for 20 years in a large cottage at the gates of his brother-in-law's estate at Bemersyde in southern Scotland, Trevor-Roper detested Scottish nationalism. He contributed a brilliant demolition of the kilt and the tartan as national symbols to a collection of essays by left-wing historians, The Invention of Tradition (1983). Other favourite targets were Oxford heads of college who opposed his successful campaign in 1960 to make Harold Macmillan Chancellor of the University, and right-wing Cambridge historians.

Three years earlier, in 1957, Macmillan had appointed Trevor-Roper Regius Professor of Modern History at Oxford. Trevor-Roper was at that time one of the most famous historians in England. Never within living memory had so many people attended an inaugural lecture, occupying every square foot of the Examination Schools. As Regius Professor for 23 years, he was a stimulating lecturer and a guide to generations of graduate students. Many found him loyal and encouraging, as well as unconventional.

The wide range of his scholarship, and personal experiences, helped him become one of the best historians of 17th-century Britain of his generation. Richard Cobb said: "He has sent far more good historians into the world of academe than other Oxford dons; and Hugh does not create disciples, rather honest and careful scholars." Trevor-Roper himself acknowledged: "I've enjoyed being Regius, I've been very happy." His accounts of Oxford in the years of student revolution, in the form of The Letters of Mercurius (1970), written in mock 17th- century prose, were unforgettable.

His years as Master of Peterhouse, Cambridge, between 1980 and 1987, were less happy. He once compared leaving Oxford for Cambridge to becoming a colonial governor, and entertaining his guests at a wedding anniversary party at Peterhouse to "bringing the beau monde to Biggleswade". Some of the college éminences grises, to whom he owed his election, and college servants, came to hate him. The Tories of Peterhouse found, to their surprise, that they had selected a Whig who believed in a mobile and plural society, and regarded all Utopias as evil. In a kinder moment, he described his enemies in the college as "members of the Trade Union of Amalgamated Troglodytes". The resulting vendettas absorbed much of his time and energy. To outsiders he often denigrated the college of which he was Master.

Hugh Trevor-Roper frequently warned against "excesses" of "useless" research, a failing of which he himself was rarely accused. He was intrigued by the uncertainties, rather than theories, of history, believed that individuals were as important as trends, that Arabs might have conquered France in the eighth century and Hitler have won the Second World War. The 30-page essay – on Prince Rupert, Matteo Ricci in China, or the culture of the Baroque Courts – was his natural form of expression. Among the best essay collections were Religion, the Reformation and Social Change (1967); The Age of Expansion (1968); Renaissance Essays (1985); and Catholics, Anglicans and Puritans (1988).

He wrote much about courts, from Henry VIII's "cannibal court" to Hitler's lunatic court in the bunker in Berlin. He based his theory of a "general crisis" in his favourite century, the 17th, on the growth of courts. Yet he never analysed their structure or nature, nor did he define the word. His private letters, written, as in the 18th- century, with the first word of the next page copied at the bottom of the previous page, may prove as enduring as many of his essays.

After retirement he lived at the Old Rectory in Didcot, Oxfordshire, devoting himself to "intellectual work during the day and dining out in the evening", in the words of his brother Patrick. Saddened by his wife's illness and death (in 1997), he kept his memory intact by reciting Dryden. The independence of his mind, the depth of his reading and the breadth of his acquaintance, which had included Lord Halifax, Bernard Berenson and Albert Speer, made his conversation seem like a voice from another age.

Trevor-Roper enjoyed the company of newspaper editors and politicians. Often telephoned by newspapers for comments on current issues, he frequented London clubs (particularly the Beefsteak) and latterly the House of Lords. Yet his sophistication did not save him from errors of judgement, especially surprising in one who devoted so much energy to pointing out those of other historians.

His ventures into art history, such as Princes and Artists (1976), were rarely entirely successful. Like his hero Gibbon, who dismissed the thousand years of the Byzantine Empire as a continuous decline, Trevor-Roper described the history of Africa as little more than "the unrewarding gyrations of barbarous, tribes in picturesque but irrelevant quarters of the globe". He himself devoted his only full-length biography after his first book, Archbishop Laud (1940), to the picturesque but irrelevant figure of Sir Edmund Backhouse, the Hermit of Peking, in A Hidden Life (1976).

When made a peer in 1979, he chose to be called Baron Dacre of Glanton, on the grounds of a kinship with the ancient Dacre line, although a hereditary Baroness Dacre already existed. The last years of his life were devoted to researching and writing a life of James I's doctor, the Huguenot Théodore Turquet de Mayenne, a brilliant if not entirely sympathetic figure, with aspirations to nobility.

Once convinced that Britain was historically part of Europe, in old age Dacre became a prophet of doom and "great convulsions", seeing the European Union as an uncompetitive economic zone, the British constitution – before the abolition of the hereditary peerage – as superior to all others. He believed that people needed an understanding of other civilisations, especially the ancient Greek, in order to stand outside "the increasingly closed world of industrial and technological society"

Just as he had at first believed Backhouse's autobiographical fantasies to be genuine (and had used one single and partly deceitful source, Albert Speer, as a basis of The Last Days of Hitler), so Dacre authenticated Hitler's diaries in 1983, despite his initial doubts and the scepticism of other historians. Misled by the volume of the archive, he wrote:

When I entered the back room in the Swiss bank and turned the pages of those volumes, my doubts gradually dissolved. I am now satisfied that the documents are authentic; that the history of their wanderings since 1945 is true; and that the standard accounts of Hitler's writing habits, of his personality and, even, perhaps, of some public events, may in consequence have to be revised.

He was not inhibited by the conflict of interest between his position as a director of Times Newspapers, and a brilliant book-reviewer for the Sunday Times, and the payment of £256,000 for UK and Commonwealth serialisation rights for the diaries already made by their parent company. At the last moment Dacre tried, but failed, to prevent the diaries' serialisation. They proved to be a crude forgery; their forger, Konrad Kujau, was later jailed in Germany.

In Selling Hitler (1986), Robert Harris pointed out that, despite the many prefaces Trevor-Roper had composed for works about the Third Reich (such as Hitler's Table-Talk 1941-44 in 1953, and The Bormann Letters of 1954), he had admitted that he did "not read German with great ease or pleasure" – least of all in the old German script. Dacre himself wrote: "Normal historical methods had been sacrificed to the necessity of a journalistic scoop." The historian who had relished publicity and controversy temporarily endured a surfeit of both.

Philip Mansel