Gillian Bennett is a British historian and civil servant, previously the Chief Historian of the Foreign and Commonwealth Office between 1995 and 2005.

After graduating from Somerville College, University of Oxford in 1969,^[1] Bennett began her career in the Foreign Office in 1972 as a research assistant in what was then called the Historical Branch.^[2] She held a number of roles within the wider FCO, and in 1995 was appointed to the newly-created position of Chief Historian.^[3] In this role, she edited the documentary history of British foreign policy since 1945, Documents on British Policy Overseas, and give historical advice to ministers and officials.^[4]

In 1998, FCO historians were commissioned by Foreign Secretary Robin Cook to investigate the authenticity of the Zinoviev Letter,^[5] and Bennett authored the report of their findings, concluding that the letter was a forgery though not likely to have been directly the work of MI6 officers.^[6][7] In researching the origins of the letter, Bennett had full access to British government sources, and also drew upon Russian archival records.^[8] Bennett retired from the civil service in 2005, and was succeeded as chief historian by Patrick Salmon.^[9]

Since 2005, Bennett has published three monographs, Churchill's Man of Mystery: Desmond Morton and the World of Intelligence (2006),^[10] Six Moments of Crisis: Inside British Foreign Policy (2013),^[11][12] and The Zinoviev Letter: The Conspiracy that Never Dies (2018).^[13][14]

• Bennett, Gill (2006). Churchill's Man of Mystery: Desmond Morton and the World of Intelligence. Government Official History Series. doi:10.4324/9780203966785. ISBN 9780415394307.
• Bennett, Gill (2013). Six Moments of Crisis: Inside British Foreign Policy. Oxford University Press. ISBN 9780199583751.
• Bennett, Gill (2018). The Zinoviev Letter: The Conspiracy that Never Dies. Oxford University Press. ISBN 9780198767305.