Heath Robinson was a machine used by British codebreakers at the Government Code and Cypher School (GC&CS) at Bletchley Park during World War II in Cryptanalysis of the Lorenz cipher.
 This achieved the decryption of messages in the German teleprinter cipher produced by the Lorenz SZ40/42 in-line cipher machine.
 Both the cipher and the machines were called "Tunny" by the codebreakers, who named different German teleprinter ciphers after fish.
 It was mainly an electro-mechanical machine, containing no more than a couple of dozen valves (vacuum tubes), and was the predecessor to the electronic Colossus computer.
 It was dubbed "Heath Robinson" by the Wrens who operated it, after cartoonist William Heath Robinson, who drew immensely complicated mechanical devices for simple tasks, similar to (and somewhat predating) Rube Goldberg in the USA.
Cryptonomicon is a 1999 novel by American author Neal Stephenson, set in two different time periods.
 One group of characters are World War II-era Allied codebreakers and tactical-deception operatives affiliated with the Government Code and Cypher School at Bletchley Park (UK), and disillusioned Axis military and intelligence figures.
 The second narrative is set in the late 1990s, with characters that are (in part) descendants of those of the earlier time period, who employ cryptologic, telecom and computer technology to build an underground data haven in the fictional Sultanate of Kinakuta.
 Their goal is to facilitate anonymous Internet banking using electronic money and (later) digital gold currency, with a long-term objective to distribute Holocaust Education and Avoidance Pod (HEAP) media for instructing genocide-target populations on defensive warfare.
Enigma is a 2001 espionage thriller film directed by Michael Apted from a screenplay by Tom Stoppard.
 The script was adapted from the novel "Enigma" by Robert Harris, about the Enigma codebreakers of Bletchley Park in the Second World War.
Michael Smith is a British author who specializes in spies and espionage.
 He is also the Bletchley Park Fellow at Kellogg College, Oxford, and a member of the board of the Bletchley Park Trust.
Banburismus was a cryptanalytic process developed by Alan Turing at Bletchley Park in England during the Second World War.
 It was used by Bletchley Park's Hut 8 to help break German "Kriegsmarine" (naval) messages enciphered on Enigma machines.
 The process used sequential conditional probability to infer information about the likely settings of the Enigma machine.
 It gave rise to Turing's invention of the "ban" as a measure of the weight of evidence in favour of a hypothesis.
 This concept was later applied in Turingery and all the other methods used for breaking the Lorenz cipher.
Alec Naylor Dakin (3 April 1912 – 14 June 2003) was a Fellow of Oxford College, a cryptologist at Bletchley Park, an Egyptologist and schoolmaster.
About 8,000 women worked in Bletchley Park, the central site for British cryptanalysts during World War II.
 Women constituted roughly 75% of the workforce there.
 While women were overwhelmingly under-represented in high-level work, such as cryptanalysis, they were employed in large numbers in important auxiliary work, such as: operating cryptographic machinery and communications machinery; translating of Axis documents; traffic analysis; clerical duties, and many more besides.
Sir Philip Stuart Milner-Barry (20 September 1906 – 25 March 1995) was a British chess player, chess writer, World War II codebreaker and civil servant.
 He represented England in chess both before and after World War II.
 He worked at Bletchley Park during World War II, and was head of "Hut 6", a section responsible for deciphering messages which had been encrypted using the German Enigma machine.
 He was one of four leading codebreakers at Bletchley to petition the then-Prime Minister Winston Churchill directly for more resources for their work.
 After the war he worked in the Treasury, and later administered the British honours system.
 In chess, he represented England in international tournaments, and lent his name to three opening variations.
Bletchley Park was the central site for British codebreakers during World War II.
 It housed the Government Code and Cypher School (GC&CS), which regularly penetrated the secret communications of the Axis Powersmost importantly the German Enigma and Lorenz ciphers.
 According to the official historian of British Intelligence, the "Ultra" intelligence produced at Bletchley shortened the war by two to four years, and that without it the outcome of the war would have been uncertain.
Susan Elizabeth Black {'1': ", '2': ", '3': ", '4': "} (born 1962) is a British computer scientist, academic and social entrepreneur.
 She has been instrumental in saving Bletchley Park, the site of World War II codebreaking, with her "Saving Bletchley Park" campaign.

Question: What specialism did Alec Naylor Dakin, fellow of Oxford College, pursue at Bletchley Park during the second World War; a central site for British codebreakers?
Answer: cryptologist