Joel Greenberg

Dr Joel Greenberg is an author and historian who has written the authorised biographies of two key figures in the story of signals intelligence, Gordon Welchman and Alastair Denniston.

The Welchman book, Gordon Welchman, Bletchley Park’s Architect of Ultra Intelligence, is the basis of a joint BBC/Smithsonian Network 2015 documentary about Welchman –The Forgotten Genius of Bletchley Park.

The Denniston book, Alastair Denniston, Code-breaking from Room 40 to Berkeley Street and the Birth of GCHQ, is both a biography and an account of signals intelligence from its early development to the birth of GCHQ. Denniston was the first Head of GCHQ and the book was launched at its headquarters on 7 September 2017 in honour of him.

He is also the author of The Bletchley Park Codebreakers in Their Own Words and the editor of a new release of Peter Calvocoressi's classic 1980 book, Top Secret Ultra.

His latest book, Alan Turing and the Enigma Code, Secrets, Lies and Myths of Bletchley Park in World War II will be published in September 2026.

Joel Greenberg received his PhD in Numerical Mathematics from the University of Manchester (UMIST) in 1973. He worked for the Open University for over 33 years, and held a number of senior management positions at Director level.