John Tiltman

Brigadier John Hessell Tiltman MC (25 May 1894 – 10 August 1982) was a British Army officer who worked in intelligence, often at or with the Government Code and Cypher School (GC&CS) starting in the 1920s. His intelligence work was largely connected with cryptography, and he showed exceptional skill at cryptanalysis. His work in association with Bill Tutte on the cryptanalysis of the Lorenz cipher, the German teleprinter cipher, called "Tunny" at Bletchley Park, led to successful attack methods. It was to exploit those methods that Colossus, the first digital programmable electronic computer, was designed and built.

Biography
Tiltman's parents were from Scotland, though he was born in London. He joined the British Army in 1914, and saw service at the front during World War I with the King's Own Scottish Borderers. He was wounded in France, and won the Military Cross for bravery. He was seconded to MI1 shortly before it merged with Room 40.

From 1921–1929, he was a cryptanalyst with the Indian Army at Army Headquarters, Simla. They were reading Russian diplomatic cypher traffic from Moscow to Kabul, Afghanistan and Tashkent, Turkestan. In the small section of five or less he was involved in all aspects, directing interception and traffic analysis as well as working on cyphers; he said he was exceptionally lucky to have this experience in other branches of Signals Intelligence.

After a decade as a War Office civilian at GC&CS, the interwar cryptographic organization, Tiltman was recalled to active service. His experience enabled him to assist in many areas of endeavour at GC&CS. He was considered one of Bletchley Park’s finest cryptanalysts on non-machine systems.

Tiltman was an early and persistent advocate of British cooperation with the United States in cryptology. His advocacy helped achieve smooth relations during World War II.

In 1944, he was promoted to Brigadier and appointed Deputy Director of GC&CS. He continued in 1946, as Assistant Director of the Government Communications Headquarters (GCHQ), successor to GC&CS. Tiltman became Senior GCHQ Liaison Officer at the Army Security Agency in 1949. He retired as a Brigadier.

In 1951 Tiltman met William Friedman, one of the leading scholars involved in the attempt to decipher the mysterious Voynich manuscript. Tiltman undertook an analysis of the ancient manuscript himself, and then in the 1970s he assigned an NSA cryptanalyst named Mary D'Imperio to take over the Voynich cryptanalysis, when Friedman's health began to fail. D'Imperio's work became the book The Voynich Manuscript: An Elegant Enigma, and is now considered one of the standard reference works on the Voynich Manuscript. Tiltman wrote the Foreword to this book.

After reaching normal retirement age, Tiltman was retained by GCHQ from 1954–1964. From 1964–1980 he was a consultant and researcher at the National Security Agency, spending in all 60 years at the cutting edge of SIGINT.

Tiltman made the transition from the manual ciphers of the early 20th century to the sophisticated machine systems of the latter half of the century; he was one of a very few who were able to do so. "The Brig" as he was affectionately known in both countries, compiled a lengthy record of high achievement.

On 1 September 2004, Tiltman was inducted into the "NSA Hall of Honor", the first non-US citizen to be recognised in that way. The NSA commented, "His efforts at training and his attention to all the many facets that make up cryptology inspired the best in all who encountered him."