EWEN Green, one of Britain's leading historians of 20th-century British Conservatism, has died aged 47. He suffered from multiple sclerosis.

The Oxford historian's contribution to our understanding of modern Conservatism is contained in three of Dr Green's exceptional books. The first, The Crisis of Conservatism: the politics, economics and ideology of the Conservative Party, 1880-1914, which appeared in 1995, examined an era in which the Tories were in the wilderness.

Dr Green's second book, Ideologies of Conservatism: Conservative political ideas in the 20th century, published in 2002, extended this approach to look at a variety of contentious policy squabbles which have divided the Tories ideologically over the past 100 years.

Particularly noteworthy was the chapter on intellectual genesis of Thatcherism, where he demonstrated that the free-market ideas that dominated the Thatcher government were not developed as a response to the dire condition of the British economy in the 1970s, but had had a constituency within the party since the Second World War. The point was hammered home in Dr Green's third book, Thatcher. The historian, a graduate of St John's College, Cambridge, ensured that his arguments were supported by archival research but his books were not weighed down by his learning, and his prose was precise and clear.

What was surprising was that he had no sympathy with 20th century Conservatism. On the left of the political spectrum, he had no love for Tory politicians.

He lectured at Reading University from 1990 to 1995, after teaching at University College, London, and St John's College, Cambridge. He also completed a research fellowship at Brasenose College, Oxford.

Following his post at Reading, he taught at Magdalen College, Oxford, where he gained a reputation as an outstanding tutor.

Dr Green also had many interests outside his studies.

He was a film buff, knew a lot about wine, and enjoyed betting on horses. He also adored dogs, and was a keen sportsman, playing rugby and cricket, before the onset of multiple sclerosis.

He continued to teach and write as long as he could, but eventually wheelchair-bound and no longer able to read, he took early retirement in Easter this year. He died on Saturday, September 16.