Alastair Denniston & GCHQ

A new book has been launched celebrating the life and achievements of the first head of GCHQ, Royal Navy Commander Alastair Denniston.

The foundations laid by the cryptanalyst at Bletchley Park were to become a key component of the Allies' victory during the Second World War (WWII).

Commander Denniston had risen to become the first head of the Government Code and Cypher School (GC&CS) during the interwar period, which was to be renamed "Government Communications Headquarters" (GCHQ) in 1946.

He identified talented individuals like Alan Turing and inspired them to become a successful team at Bletchley Park.

We spoke to author Joel Greenberg about his new book, which charts Cdr Denniston's career...


Cdr Denniston is credited with understanding the value which could be brought to signals intelligence by people with neurodiverse conditions if they were allowed to be themselves – a skill still practised by today's GCHQ.

A bronze medallist at the 1908 London Olympics in field hockey, he was recruited to 'Room 40', a section in the British Admiralty which deciphered coded messages, from a job teaching French and German at the Royal Naval College.

Alastair Denniston
Denniston with his family and in his Navy uniform. Pictures used with kind permission of Judith Finch (granddaughter)

He then served there during the First World War (WWI), when the group famously intercepted and decoded the German Zimmermann Telegram, which helped bring the US into the war.

Room 40 was deactivated in 1919 and merged with the British Army's intelligence unit MI1b to form GC&CS. Tony Comer, GCHQ historian, said:

"In many ways, Denniston was a 'forgotten man' but, thanks to this book, he will be forgotten no more."

"He was the first person to lead the organisation and his vision for signals intelligence, along with the culture he fostered, enabled the team at Bletchley Park to read Enigma encrypted messages on an industrial scale.

"The values he promoted of ingenuity, teamwork, and authenticity, are ones that still bind today's GCHQ. This book rightly positions him as the giant of signals intelligence and the innovator that he was."

Although GC&CS concentrated largely on reporting diplomatic traffic, it was with Denniston’s agreement that the first commercial Enigma machine was bought in 1926 and he later recognised the importance of the cryptanalytical advantage the French and Poles could bring, which would be the foundation of Bletchley Park's success.

He also oversaw the move by GC&CS from London to Bletchley Park in 1939 and led the establishment of closer liaison with the US, which preceded the special relationship the countries enjoy today.

Charles Dance
Cdr Denniston was played by actor Charles Dance in hit film 'The Imitation Game'. Picture: Alan Chang

He remained Head of GC&CS until 1942 and retired in 1945. 

Cdr Denniston became the subject of controversy in 2014 when his grandchildren claimed he was unfairly depicted as a bullying "baddy" in box office hit The Imitation Game.

Judith Finch, his granddaughter, was quoted in the Telegraph as saying: "He is completely misrepresented. They needed a baddy and they've put him in there without researching the truth about the contribution he made." 

Take a look below at his portrayal in the film's trailer...

The makers of the film later said The Imitation Game simply showed the "natural conflict of people working extremely hard under unimaginable pressure" and paid tribute to "one of the great heroes of Bletchley Park", however.

Titled Alastair Denniston: Code-Breaking from Room 40 to Berkeley Street and the Birth of GCHQ", the new book was written with the support of both the Denniston family and GCHQ, however. 

It's available through Frontline Books for £25.

Cover photo courtesy of GCHQ/Crown Copyright.

More: Answers To GCHQ Cryptic Christmas Code Revealed