Goldsmiths’ 2014 Mathematics

Wednesday 23rd July

Tour of Bletchley Park

Once Britain’s Best Kept Secret, today Bletchley Park is a heritage site and vibrant tourist attraction. Open daily, visitors can explore some of the iconic WW2 Codebreaking Huts and Blocks and marvel at the astonishing achievements of the Codebreakers whose work is said to have helped shorten the war by two years.

Interactive activities

The codebreaking process – signals intelligence

If you can find out what your enemy is planning you have a huge advantage. Military commanders know you need to use codes or ciphers so that if messages fall into enemy hands they make no sense and your plans stay secret.

In WW2, Germany knew its wireless (radio) messages would be intercepted. Britain and its allies had done this in WW1 and gained information so secret that it was known only as “Special Intelligence” later called Signals Intelligence. But the Germans now believed that by using modern cipher machines such as Enigma, their messages could never be unscrambled. They were wrong.

Using a process involving six separate stages, the Codebreakers turned encrypted signals into priceless intelligence.

1) Intercept your enemies’ radio signals

Eavesdrop on messages going to and from enemy headquarters and army, navy and air forces in the field.

2) Work out how the messages have been encrypted

Look carefully at the messages and use brainpower and intuition; together with the new machines you’ve invented, to break the day’s ciphers.

3) Decipher

Once the cipher has been obtained then it needs to be deciphered.

4) Translate

Use language specialists to turn deciphered messages into English so that intelligence experts can assess how important they are.

5) Cross reference

See if anything in the message relates to other facts you know, to help build a better picture of what your enemy is doing.

6) Send on the top secret intelligence you have uncovered

Make sure the information gets to the right people. Which senior military commander will it help? Is it something the Prime Minister needs to know?


The above images show an Enigma machine and other code braking equipment.

Tour of Bletchley Park with John Wilson



We started out tour in the chauffer’s hut with a talk by Mr. Wilson.

Bletchley Park is 80km northwest of London and the site appears in the Domesday Book as part of the Manor of Eaton. A mansion was built there in 1711 by Browne Willis (16 September 1682 – 5 February 1760, an antiquary, author, numismatist and politician who sat in the House of Commons from 1705 to 1708) which was pulled down by Thomas Harrison in 1793. It was first known as Bletchley Park after its purchase by Samuel Lipscomb Seckham in 1877, who created a farm there.

The estate of 235 ha was bought in 1883 by Sir Herbert Samuel Leon, who expanded the then-existing farmhouse into the present “maudlin and monstrous pile” combining Victorian Gothic, Tudor, and Dutch Baroque styles.

Sir Herbert Samuel Leon (11 February 1850 – 23 July 1926) was an English financier and Liberal Party politician. He was elected as the Member of Parliament (MP) for Buckingham at a by-election 1891 and he was a great friend of David Lloyd George.

Leon served as High Sheriff of Buckinghamshire in 1909 and was created a baronet in the 1911 Coronation honours. He died in 1926 and when his second wife died the estate consisted of 581 acres, 147 staff, 40+ gardeners and two Rolls Royce cars.

The estate was divided into lots and sold off by Knight Frank but the mansion lot did not reach its reserve.

A private deal was made to enable a housing estate to be built but in May 1938 Admiral Sir Hugh Sinclair, head of the Secret Intelligence Service (SIS or MI6) bought the mansion and 23 ha for use by GC&CS and SIS in the event of war. War seemed very likely after Germany annexed Austria and invaded Czechoslovakia, and Bletchley Park started to recruit staff including Captain William Ridley and Commander Alastair Denniston.

After Neville Chamberlain’s “peace in our time” meeting with Adolf Hitler in September 1938 Captain Ridley returned to London.

When war was declared staff returned and Commander Denniston became operational head of GC&CS (now GCHQ) there.

The team at Bletchley Park broke codes and cyphers.

A code replaces words or phrases by other words and phrases.

A cypher replaces individual letters or numbers by other letters and numbers.

Machines were used to develop cyphers and Bletchley Park was really involved in cypher breaking (not code breaking).


In the above picture you can see Mr Wilson on the right and Dr Wright (in an interesting hat) by the main gate used during World War 2. In the early stages of the war a lot of the staff, who would have passed through this gate, came from Cambridge University but over time many people from different walks of life, such as bank managers and teachers, came to work there.

Bletchley Park was a unique multi-unit intelligence site which was excellent as the experts there could keep in contact with each other. Germans had their intelligence centres spread over 14 sites which was, thankfully, a big problem.

At the start of the war the Germans were much more effective at intelligence but as the war progressed the British got better and they got worse. According to Mr Wilson the British can be a bit dozy.

Bletchley Park was the forerunner factory of industrial code breaking. It had the first digital computer.

Colossus was the world’s first electronic digital computer that was at all programmable. The Colossus computers were developed for British codebreakers during World War II to help in the cryptanalysis of the Lorenz cipher.


The above image shows Colossus Mark 2 computer being operated by Dorothy Du Boisson (left) and Elsie Booker. The slanted control panel on the left was used to set the “pin” (or “cam”) patterns of the Lorenz. The “bedstead” paper tape transport is on the right.

In 1942 the dining room was moved from the mansion to a designated hut to be able to sit more people. There could be 1000 people at a sitting.


Staff did not live on the site but commuted in from the surrounding area. However there was staff present 24 hours a day. 9000 people worked in three shifts on site plus outstations.

There was an assembly hall on site which held meetings, lectures and amateur dramatics.


Ian Fleming, who created James Bond, was based in hut 12. He worked for naval intelligence and was responsible for liaising with Bletchley Park.

Ian Lancaster Fleming (28 May 1908 – 12 August 1964) was an English author, journalist and naval intelligence officer, best known for his James Bond series of spy novels.



The Mansion at Bletchley Park is a 66+ room grade 2 listed building. It consists or 19 architectural styles with the date ‘1883’ and monogram ‘HSL’ over the main entrance of the house indicating when Leon started to make changes to the mansion.

In October 1941 after receiving a letter from some of the senior codebreakers decrying the lack of resources being afforded them, Prime Minister Winston Churchill directed:

‘Make sure they have all they want extreme priority and report to me that this has been done.’

From that moment on Bletchley Park began receiving a huge influx of resources and a major building programme ensued to create the space necessary to house the ever increasing workforce.

In 1942 Denniston was moved sideways and Edward Travis RN took over for the rest of the war.

Sir Edward Wilfred Harry Travis KCMG CBE (24 September 1888 – 23 April 1956) was a British cryptographer and intelligence officer, becoming the operational head of Bletchley Park during World War II, and later the head of GCHQ.


The above picture is of a nice lady called (a volunteer at Bletchley Park) who lived at Bletchley Park during the war as a young child because her father was head of services.

A key advantage seen by Sinclair and his colleagues (inspecting the site under the cover of “Captain Ridley’s shooting party”) was Bletchley’s geographical centrality. It was almost immediately adjacent to Bletchley railway station, where the “Varsity Line” between Oxford and Cambridge – whose universities were expected to supply many of the code-breakers – met the main West Coast railway line connecting London, Birmingham, Manchester, Liverpool, Glasgow and Edinburgh. Watling Street, the main road linking London to the north-west (now the A5) was close by, and high-volume communication links were available at the telegraph and telephone repeater station in nearby Fenny Stratford.

Bletchley Park was known as “B.P.” to those who worked there. “Station X”, “London Signals Intelligence Centre”, and “Government Communications Headquarters” were all cover names used during the war. (The formal posting of the many “Wrens” – members of the Women’s Royal Naval Service – working there was to HMS Pembroke V.)

Bletchley Park had its own telegram cable, water and electricity supplies,


Initially, a wireless room was established at Bletchley Park. It was set up in the mansion’s water tower under the code name “Station X”, a term now sometimes applied to the codebreaking efforts at Bletchley as a whole. The “X” is the Roman numeral “ten”, this being the Secret Intelligence Service’s tenth such station. Cables from the water tower and aerials were supported by a big sequoia tree in front of the mansion. The iron supports are still there.


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.

Special operations executive (SOE) was also based at Bletchley Park

The Special Operations Executive (SOE) was a British World War II organisation. Following Cabinet approval, it was officially formed by Minister of Economic Warfare Hugh Dalton on 22 July 1940, to conduct espionage, sabotage and reconnaissance in occupied Europe against the Axis powers, and to aid local resistance movements.

SIS (also known as MI6) was also based at Bletchley Park

The Secret Intelligence Service (SIS), commonly known as MI6 (Military Intelligence, Section 6), is the British intelligence agency which supplies the British Government with foreign intelligence. It operates under the formal direction of the Joint Intelligence Committee (JIC) alongside the internal Security Service (MI5), the Government Communications Headquarters (GCHQ) and Defence Intelligence (DI)


Bletchley doesn’t have a post office as such but you can buy special stamps there and it has its own franking mark.

Station X was classed as a diplomatic radio because Britain didn’t want to admit having spies. It was designated X because it was the tenth station and X is the Roman numeral for ten.

It was intended to be a duplicate of the original SIS wireless “station X” at Barnes in west London but everything was transferred to Bletchley Park.

At the start of the Second World War the United States was neutral so couldn’t be seen to help Britain. William Stephenson was sent to the US by the head of SIS to see if it the friendly relationship could be rekindled to an extent that SIS could operate effectively in the US. While J. Edgar Hoover was sympathetic he could not go against the State Department without the President’s authorisation; he also believed that if so authorised, it should be a personal liaison between Stephenson and himself without other departments being informed. In the event Roosevelt did endorse the co-operation.

The liaison was necessary because Britain’s enemies were already present in the US and could expect sympathy and support from German and Italian immigrants but the authorities there had neither remit nor interest in activities that were not directly against US security.

Stephenson’s report on the American situation advocated a secret organisation acting beyond purely SIS activities and covering all covert operations that could be done to ensure aid to Britain and an eventual entry of the US into the war. Stephenson was given this remit and the traditional cover of appointment as a ‘Passport Control Officer’ which he took up in June 1940.

Sir William Samuel Stephenson, KBE, CC, MC, DFC (23 January 1897 – 31 January 1989) was a Canadian soldier, airman, businessman, inventor, spymaster, and the senior representative of British intelligence for the entire western hemisphere during World War II.



In the above picture you can see one of the other main entrances used by despatch riders to the site. At the end there is a sentry box that could have contained two armed guards.

Listening stations were placed along the east and south coast. Known as Y-stations, they included Chicksands in Bedfordshire, Beaumanor Hall, Leicestershire (where the headquarters of the War Office “Y” Group was located) and Beeston Hill Y Station in Norfolk and were responsible for gathering raw signals for processing at Bletchley. Coded messages were taken down by hand and sent to Bletchley on paper by motorcycle despatch riders (more often than not, ladies) or (later) by teleprinter. Y stations were minded by waafs. Waafs had many duties including listening to cyphered Morse code. They worked with codes and ciphers, analysed reconnaissance photographs, and performed intelligence operations.

The Women’s Auxiliary Air Force (WAAF), whose members were invariably referred to as WAAFs, was the female auxiliary of the Royal Air Force during World War II, established in 1939. At its peak strength, in 1943, WAAF numbers exceeded 180,000, with over 2,000 women enlisting per week.’s_Auxiliary_Air_Force

A mistake made by the Germans was to re-send a message when the original hadn’t got through because of phase shift fading using the exact same code as before. The British were able to pick up both messages and decode them more easily.

In 1944 up to 4000 messages were decoded per day but this increased to 18000 enigma messages after operation overlord.

Operation Overlord was the code name for the Battle of Normandy, the Allied operation that launched the successful invasion of German-occupied Western Europe during World War II. The operation commenced on 6 June 1944 with the Normandy landings (Operation Neptune, commonly known as D-Day).

Throughout the war Bletchley Park did suffer from not having enough staff.

Most German messages decrypted at Bletchley were produced by one or another version of the Enigma cipher machine, but an important minority were produced by the even more complicated twelve-rotor Lorenz SZ42 on-line teleprinter cipher machine.

The Lorenz SZ40, SZ42A and SZ42B were German rotor stream cipher machines used by the German Army during World War II. They were developed by C. Lorenz AG in Berlin and the model name SZ was derived from Schlüsselzusatz, meaning cipher attachment. The instruments implemented a Vernam stream cipher.

British cryptographers, who referred to encrypted German teleprinter traffic as Fish, dubbed the machine and its traffic Tunny,


The above image shows a Lorenz SZ42 machine with its covers removed.

Wireless telegraphy (WT) rather than land-line circuits was used for this traffic. These non-Morse (NoMo) messages were picked up by Britain’s Y-stations at Knockholt and Denmark Hill and sent to Government Code and Cypher School at Bletchley Park (BP). Some were deciphered using hand methods before the process was partially automated, first with Robinson machines and then with the Colossus computers. The deciphered messages made an important contribution to Ultra military intelligence.

Bletchley Park staff only saw a Tunny machine in 1945, shortly before the allied victory in Europe.

The T-52 was an electro-mechanical cipher machine for teleprinter signals (telex) developed by Siemens & Halske around 1930. It was one of the main cipher machines of the German Army during WWII, being used alongside the Enigma, the Lorenz SZ-40 and later the T-43. After the war, the machine was used in a number of countries, including France and The Netherlands.


Capturing secret code books was a key to breaking Axis codes. In 1940 the crew of a captured German ship threw their code books overboard, but the British Royal Navy managed to recover some of them.

U-110 was captured by the Royal Navy on May 9, 1941. The boarding party commanded by Lt David Balme made several journeys between U-110 and HMS Bulldog to collect whatever they could get their hands on inside the boat. This proved to be very fruitful, as U-110 was abandoned in a hurry, and being a type IXB U-boat, did not sink as rapidly as a type VIIC would have. It is almost certain that many U-boats were sunk as a result of the material found inside U-110, including an Enigma machine with rotors set, and current code books.

In 1942 British sailors recovered code books from a sinking U-boat in the Mediterranean Ocean. Two British sailors died, but the books they rescued allowed cryptanalysts to solve German codes used to communicate with submarines in the Atlantic.

With captured code books and skilled code breaking, the Allies were reading up to four thousand Enigma intercepts every day by the end of 1942. These and similar technological victories helped the Allies stem the tide of U-boat attacks on vital supply convoys.

The German Navy, rightly suspicious that their code had been cracked, introduced a fourth wheel into the device, multiplying the possible settings by twenty six. The British finally broke this code that they called ‘Shark’ in December 1942.


The garage seen in the image above was built for Sir Herbert’s two Rolls Royce motor cars. During the war it housed military vehicles, fire engines and Commander Denniston’s Rover car.

In the image below Mr Wilson is standing in the stable yard and the house behind him was originally the head groom’s house.


The above pictures show what were the tack and feed houses, converted just before the war to two cottages. Joan Budd, who we met earlier, lived at cottage number 2 with her family. In the top room of the cottage on the right (number 3) is where Alan Turning worked. It is also where Dilly Knox and John Jeffreys worked on the ideas for breaking Enigma that they had gained from the Poles at the famous meeting in the Pyry forest in Poland, 25 July 1939.


Alan Mathison Turing, OBE, FRS (23 June 1912 – 7 June 1954) was a British mathematician, logician, cryptanalyst, philosopher, computer scientist, mathematical biologist, and marathon and ultra-distance runner. He was highly influential in the development of computer science, providing a formalisation of the concepts of “algorithm” and “computation” with the Turing machine, which can be considered a model of a general purpose computer. Turing is widely considered to be the father of theoretical computer science and artificial intelligence.”

John Jeffreys set up a production line to make copies of the Polish ‘Zygalski Sheets.’ One set of these was taken by Alan Turing to Chateau Vignolles just outside Paris. The Polish mathematicians, Rozecki, Zygalski and Rejewski, had escaped there from Poland.

The first break back into Enigma occurred at Vignolles in January 1940 using the sheets Jeffreys took.

A few weeks later the German Air Force key, known as RED, was broken in the cottage. Immediately the cottage was quarantined to keep the breaking of Enigma absolutely secret.

Mr Wilson talked about agents during the war and that his headmaster, Captain Ray Evans, had been one. Because Germans could triangulate radio signals agents used pigeons to send and receive messages. There was always a risk that the pigeons would be killed. Bletchley Park had a pigeon loft and you can see it in the image below shows the building that was once the pigeon loft.


The picture below shows what was the apple and plum store was also converted to two flats before the war.


Bletchley Park had the most success reading the Luftwaffe messages, codenamed “Red” by the British cryptographers. It was broken on May 22, 1940, and was read uninterrupted throughout the rest of the war. This was largely because the volume of intercepts and different cribs was very high. A red code set consisted of 1 send and 1 receive and there were 100s of sets.

Throughout the war the British airforce and British navy were considered adjuncts to the army. The airforce was considered as simply flying artillery.

Mavis Lilian Batey, MBE (née Lever; 5 May 1921 – 12 November 2013), was an English code-breaker at Bletchley Park during World War II. Her work was one of the keys to the success of D-Day.

In December 1941 she broke a message between Belgrade and Berlin that enabled Dilly Knox’s team to work out the wiring of the Abwehr Enigma, an Enigma machine previously thought to be unbreakable. She was closely involved in the decryption effort before the Battle of Matapan.

The Battle of Cape Matapan was a Second World War naval engagement fought from 27–29 March 1941. The cape is on the southwest coast of Greece’s Peloponnesian peninsula. Acting on intercepted signals broken by the Government Code and Cypher School (GC&CS) at Bletchley Park, a force of British Royal Navy ships accompanied by several Royal Australian Navy vessels, under the command of British Admiral Andrew Cunningham, intercepted and sank or severely damaged several ships of the Italian Regia Marina under Admiral Angelo Iachino.

The opening actions of the battle are also known in Italy as the Battle of Gaudo.

The Polish War Memorial


Bletchley’s Polish Memorial, commemorating “the [prewar] work of Marian Rejewski, Jerzy Różycki and Henryk Zygalski, mathematicians of the Polish intelligence service, in first breaking the Enigma code. Their work greatly assisted the Bletchley Park code breakers and contributed to the Allied victory in World War II.”

Hans-Thilo Schmidt (13 May 1888 – 19 September 1943) codenamed Asché or Source D, was a spy who, during the 1930s, sold secrets about the Germans’ Enigma machine to the French. The materials he provided facilitated Polish mathematician Marian Rejewski’s reconstruction of the wiring in the Enigma’s rotors and reflector; thereafter the Poles were able to read a large proportion of Enigma-enciphered traffic. He did this at a time when German defence budgets were slashed and he thought he could earn some money.

In December 1932, the Polish Cipher Bureau near Warsaw received from Gustave Bertrand of French Military Intelligence, two German documents and two pages of Enigma daily keys which had been obtained by the French from Hans-Thilo Schmidt. This material enabled Marian Rejewski to achieve “one of the most important breakthroughs in cryptologic history” by using the theory of permutations and groups to work out the Enigma scrambler wiring.


Marian Adam Rejewski (16 August 1905 – 13 February 1980) was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany.

On 15 December 1938, the German Army increased the complexity of Enigma enciphering by introducing two additional rotors (IV and V). This increased the number of possible wheel orders from 6 to 60. This made the cryptanalysis ten times more difficult.

In 1939 as it was becoming clear that war was imminent the Polish government handed over all their enigma work to the British. This cut 2 years off the length of the war.

There are lots more at Bletchley Park than I haven’t written about because we ran out of time. I would thoroughly recommend you visit if you haven’t been already.

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