Lewis Namier was born Ludwik Bernsztajn, at Wola Okrzejska in Poland of non-practising Jewish parents, in 1888. He was educated at Lwow and Lausanne universities, before coming to Britain in 1907 to study at the London School of Economics; this was followed by a period at Balliol College, Oxford. He graduated with first class honours in modern history from Oxford in 1911. After changing his name to Lewis Bernstein Naymier in 1909, Namier took British nationality in 1913 and modified his surname to Namier. For a short period before the war, he worked in business in New York.
From 1915 Namier was employed at the Ministry of Information, latterly in the Political Intelligence Department, which was incorporated into the Foreign Office in 1917 . He resigned in 1920 and returned to Balliol as a part-time tutor, but had to re-enter business in 1921 to amass funds to continue his research. He became the European representative of a firm of Manchester cotton manufacturers, and was based in Czechoslovakia. He also speculated on the Viennese stock exchange, and worked as an occasional correspondent for the Manchester Guardian and the Manchester Guardian Commercial.
From 1924 to 1929 he was able to work full-time on his historical research, the result of which were two volumes of eighteenth-century British history; The structure of politics at the accession of George III (1929) and England in the age of the American revolution (1930). These were immediately recognised as works of great significance, and constitute Namier's lasting achievement. His views of eighteenth-century politics were controversial: he rejected the view that George III was trying to restore royal absolutism; denied that politics revolved around Whig and Tory 'parties'; and took a less censorious view of political 'corruption' than many of his predecessors. Namier's views on historical method were also influential, with an emphasis on understanding political actions through the role of institutions and the collective biography of the ruling elite rather than relying on studying the political ideas which were held to motivate them. These views marked him out as an effective critic of the so-called 'Whig interpretation of history'. His commitment to massively detailed archival research, of which he was a pioneer, was also influential within the historical profession.
In 1931 Namier finally achieved a full-time academic post when he became professor of modern history at Manchester University. Much of his later work was in the form of essays and lectures, particularly relating to nineteenth-century European history. His main interests were the working of legislative assemblies and the growth of modern nationalism, and he was much exercised by the contrast between the relative political stability he saw in eighteenth-century parliamentary Britain and the breakdown of political order in twentieth-century Europe, which he traced to the effects of nationalist ideologues. In 1946 he published 1848: the Revolution of the Intellectuals, an expanded version of his Raleigh lecture of 1944. He also published studies of Nazism and appeasement in the 1930s, of which he had been an outspoken critic, notably Diplomatic Prelude: 1938-1939 (1948), andEurope in Decay: A Study in Disintegration, 1936-1940 (1950).
In 1951 Namier returned to his original interest of British parliamentary history, joining the Editorial Board of the History of Parliament Trust. His involvement with this project dated back to the late 1920s, and he had been a member of the committee which had reported to Parliament on the feasibility of multi-volume history of parliament. After he retired from Manchester in 1953, the rest of Namier's life was taken up with running this project. He researched the period 1754-1790, and his three-volume study,The History of Parliament: The House of Commons 1754-1790 was published in 1964. This work summed up Namier's approach to historical writing, with its highly detailed studies of every single M.P. and their constituencies. A biography of Charles Townshend, written in collaboration with John Brooke, was published posthumously in 1964.
Namier was actively involved in politics and public life throughout his career. He was a passionate Zionist, and in 1929 became political secretary for the Zionist Organisation/Jewish Agency of Palestine. During the 1930s, Namier did much to help Jewish emigrants from Nazism. Namier was knighted in 1952. He was twice married and died in London in 1960.
As a historian, Namier was unusual in having experience of business and politics, which influenced his approach to history. He enjoyed controversy and often expressed himself in a deliberately provocative manner, believing that all good historians should be iconoclasts. Although as a young man he had been a strong socialist, he was never a Marxist and as he became older his sympathies were became much more Conservative: these political views, and his early pan-Slavist enthusiasm, informed his historical writings. He was capable of arousing strong feelings, both for and against his opinions. A perfectionist regarding thorough empirical research, Namier was only able to publish a fragment of his intended output. Methodologically he was one of the most significant British historians of the twentieth century, his influence being confirmed by the Oxford English Dictionary in 1976, when it recognised the noun, 'Namierite' and the adjective 'Namierian'.