During World War II, Turing worked for the Government Code and Cypher School ( GCCS ) at Bletchley Park, Britain's codebreaking centre.

Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Codes Centre and the National Museum of Computing.

During the Second World War, Bletchley Park was the site of the United Kingdom's main decryption establishment, the Government Code and Cypher School ( GC & CS ), where ciphers and codes of several Axis countries were decrypted, most importantly the ciphers generated by the German Enigma and Lorenz machines.

The high-level intelligence produced at Bletchley Park, codenamed Ultra, provided crucial assistance to the Allied war effort.

A large portion of the site is now controlled by the Bletchley Park Trust.

The Bletchley Park Science and Innovation Centre ( BPSIC ) refurbished some of the historic structures and occupies part of the former code-breaker buildings.

The lands of the Bletchley Park estate were formerly part of the Manor of Eaton, included in the Domesday Book in 1086.

The estate was first known as Bletchley Park during the ownership of Samuel Lipscomb Seckham, who purchased it in 1877.

Leon's estate covered, of which Bletchley Park occupied about.

To cover their real purpose, the first government visitors to Bletchley Park described themselves as " Captain Ridley's shooting party ".

The first wave of the Government Code and Cypher School ( GC & CS ) moved to Bletchley Park on 15 August 1939.

Both of the two German electro-mechanical rotor machines whose signals were decrypted at Bletchley Park, Enigma and the Lorenz Cipher ', were virtually unbreakable if properly used.

A number of American cryptographers were posted to Bletchley Park and were inducted and then integrated into the Ultra structure, being stationed in Hut 3.

Conversely, the existence of Bletchley Park, and of the decrypting achievements there, was never officially shared with the Soviet Union, whose war effort would have greatly benefited from regular decrypting of German messages relating to the Eastern Front.

Some 9, 000 people from the armed services and civilians were working at Bletchley Park at the height of the codebreaking efforts in January 1945, and over 12, 000 ( of whom more than 80 % were women ) worked there at some point during the war.

Knowing that the slightest suspicion by the Axis powers that their ciphers were being broken, could lead to such a change, the authorities at Bletchley Park were extremely concerned about security.

Initially, a wireless room was established at Bletchley Park.

Due to the long radio aerials stretching from the wireless room, the radio station was moved from Bletchley Park to nearby Whaddon Hall to avoid drawing attention to the site.

Even though the goal has been the same, the methods and techniques of cryptanalysis have changed drastically through the history of cryptography, adapting to increasing cryptographic complexity, ranging from the pen-and-paper methods of the past, through machines like Bombes and Colossus computers at Bletchley Park in World War II, to the mathematically advanced computerized schemes of the present.

* Cragon, Harvey G. From Fish to Colossus: How the German Lorenz Cipher was Broken at Bletchley Park ( Cragon Books, Dallas, 2003 ; ISBN 0-9743045-0-6 ) – A detailed description of the cryptanalysis of Tunny, and some details of Colossus ( contains some minor errors )

* Enever, Ted Britain's Best Kept Secret: Ultra's Base at Bletchley Park ( Sutton Publishing, Gloucestershire, 1999 ; ISBN 0-7509-2355-5 ) – A guided tour of the history and geography of the Park, written by one of the founder members of the Bletchley Park Trust

A reconstructed working copy of one of the Colossus machines is now on display at Bletchley Park.

A few miles further on it enters Milton Keynes at the outskirts of Bletchley at Fenny Stratford Lock, which is unusual in lowering the level by only 12 inches ( 30 cm ).

After Bletchley Manor, there is of dual carriageway.

From this tradition, the name Ascalon was used by Winston Churchill for his personal aircraft during World War II ( records at Bletchley Park ), since St. George is the Patron Saint of England.

It is probable that he was posted to Bletchley Park by MI6, as assignments there were not by request.

He was also depicted in part three of the 2003 BBC TV series Cambridge Spies, where he appears reluctant to continue passing Bletchley Park data to the Russians for fear that the Red Army was heavily penetrated by German intelligence and by Eastern Front military intelligence under General Gehlen ; Anthony Blunt is depicted in the drama as pressuring him with threats to continue.

Image: Bletchley Park. jpg | The façade at Bletchley Park, United Kingdom is a mix of architectural styles.

Buckinghamshire Railway Centre is rail-connected because Quainton Road station is on the Network Rail freight-only line ( formerly a mainline used jointly by the Great Central Railway and the Metropolitan Railway through the Metropolitan and Great Central Railways Joint Committee ) which connects Aylesbury with the Bletchley to Oxford cross-country route at Claydon ( LNE ) Junction.

Bletchley is a constituent town of Milton Keynes, in Buckinghamshire, England.

It is situated in the south-west of Milton Keynes, and is split between the civil parishes of Bletchley and Fenny Stratford and West Bletchley.

Bletchley is best known for Bletchley Park, the headquarters of Britain's World War II codebreaking organisation, now a museum.

Drayton Parslow is a village and civil parish in the Aylesbury Vale district of Buckinghamshire about south of Bletchley.

Fenny Stratford is a constituent town of Milton Keynes, ceremonial county of Buckinghamshire, England and in the Civil Parish of Bletchley and Fenny Stratford.

There is a plaque commemorating this at the westerly end of Denmark Street in Fenny Stratford opposite The Foundry public house-though the location of Akroyd Stuart's workshop is usually given as " Bletchley ", which is a larger town adjoining Fenny Stratford.

The sheets were known at Bletchley as Netz ( from Netzverfahren, " net method "), though they were later remembered by Gordon Welchman as " Jeffreys sheets "; the latter term, however, referred to another catalog produced by Jeffreys ' section.

Lucas is also remembered for his wartime work at Bletchley Park.

The only direct enemy action that the site experienced was when 3 bombs, thought to have been intended for Bletchley railway station, were dropped on 20 – 21 November 1940.

Subsequently, other listening stations – the Y-stations, ( such as the ones at Chicksands in Bedfordshire and Beaumanor Hall in Leicestershire where the headquarters of the War Office " Y " Group was located ) – gathered raw signals for processing at Bletchley.

He made enquiries, and was approached to work for the Government Code & Cypher School at Bletchley Park.

Leo Marks describes inventing such a system for the British Special Operations Executive during World War II, though he suspected at the time that it was already known in the highly compartmentalized world of cryptography, as for instance at Bletchley Park.

Ultra was the designation adopted by British military intelligence in June 1941 for wartime signals intelligence obtained by breaking high-level encrypted enemy radio and teleprinter communications at the Government Code and Cypher School at Bletchley Park.

Despite returning several times, Orwell was characteristically acerbic about his time in Hayes, camouflaging it lightly as West Bletchley in Coming Up for Air, as Southbridge in A Clergyman's Daughter, and joking in a letter to author / friend Frank Jellinek:

It also formed one of the Y-stations used to gather Signals Intelligence via radio transmissions which, if encrypted, were subsequently passed to Bletchley Park for decryption.

* George Bowling, the main character in Coming Up for Air by George Orwell, lived in Ealing before moving to West Bletchley.

* The cryptanalytic effort undertaken by the Government Code and Cypher School ( GC & CS ), the bureau responsible for interception and decryption of foreign communications at Bletchley Park.

The line was not finished in time for the coronation of Queen Victoria on 28 June 1838, but aware of the lucrative traffic the event would generate, the company opened the north end of the line, between Birmingham and Rugby, and the south end from London to Bletchley with a stagecoach shuttle service linking the two parts to allow through journeys to London.

** John Cairncross, British agent working for the Soviets ; worked at Bletchley Park and gave information to the KGB.

The parallel Enigma-enciphered link to NoMo2, which was being read by Government Code and Cypher School at Bletchley Park, revealed that the Germans called the wireless teleprinter transmission systems " Sägefisch " ( sawfish ), so the name " Fish " was adopted for this traffic.

The NoMo1 link was initially named Tunny, a name which later went on to be used both for the Lorenz SZ40 / 42 Geheimschreiber machines, and also for the Bletchley Park analogues of them.

Later, he joined the codebreakers at Bletchley Park, and by 1945 was one of some fifteen mathematicians working in the " Newmanry ", a section headed by Max Newman and responsible for breaking a German teleprinter cipher using machine methods.

A single-track freight line from Bletchley to Bicester was retained and then abandoned in place in 1993 ; the track remains rusted beyond use and in overgrown state, although modern signage still warns travellers to watch for approaching trains.

Bletchley railway station was for many years an important node on the railway.

It was The Plan for Milton Keynes that would bring the most dramatic change to the future of Bletchley.