Duncan Tanner, who has died suddenly of a heart condition, aged 51, was one of the most respected historians of his generation. He made his mark by revolutionising our understanding of who had the vote – and who did not – in early-20th-century Britain. His first book, Political Change and the Labour Party 1900-1918 (1990), cemented his reputation as a leading Labour historian with a work of massive and impregnable scholarship.
In the last decade of his life, his research interests were still broadening. Based at Bangor University, he became director of the new Welsh Institute for Social and Cultural Affairs. He was the driving force of a team working on the history of Welsh devolution and co-edited the project’s first volume, Debating Nationhood and Government in Britain, 1885-1939 (2006). He was working on the second volume at the time of his death.
Born in Newport, south Wales, Tanner went from his local state school to Royal Holloway College, University of London, where he obtained a first-class degree in modern history and politics in 1979, followed by a PhD at University College London. After research fellowships at the Institute of Historical Research, London, and St Catharine’s College, Cambridge, he secured a lectureship at Bangor in 1989, and within seven years had risen to become head of the school of history and Welsh history. Recognised for his managerial talents, he became director of research at Bangor in 2008.
Throughout these busy years, he published widely on inter-war Labour history. He co-edited two important volumes marking the centenary of the Labour party, The Labour Party in Wales, 1900-2000 (2000) and Labour’s First Century (2000), and a further volume of wide-ranging essays, The Strange Survival of Liberal England (2007). A passionate Welsh rugby supporter, he even found time for thoughtful work on sport and national identity in Wales.
Tanner became a leading authority on the Freedom of Information Act, urging historians to use it to push forward the boundaries of investigation. His expertise was recognised by numerous editorial advisory boards, and at the time of his death he was editor of the journal Twentieth Century British History.
An initial stolidity of manner belied Duncan’s underlying warmth. He was a charismatic and enthusiastic teacher, combining academic rigour with infectious wit. To his many former PhD students (he was proud of his 100% success record as a research supervisor), he was a patient, inspirational mentor who took pride in their careers.
His technical accomplishment as a scholar sometimes masked the full originality of his insights. Disdaining show or artifice, he was a historian who produced groundbreaking work.
Tanner is survived by his wife, Christine, and daughters, Eleanor and Megan.
• Duncan Martin Tanner, historian, born 19 February 1958; died 11 February 2010