Probus Club of Ewell visit to Bletchley Park
Monday 14th March 2011
It was a frosty but sunny morning when 25 of us left Epsom at 9am for an eighty mile journey to Bletchley Park near Milton Keynes.
We were met, at 11am, by our guide for the day, John Miller, a retired insurance broker, outside the Grade II listed building known as the Mansion. All guides are volunteers to the Bletchley Park Trust, a charity organisation that receives no Government funding except from a Lottery grant.
After forming up for a formal photo shoot then entered the drawing room for tea/coffee and biscuits and an introductory talk
John gave us a brief history of Cryptography, Codes and Computers – how it involved sending messages by transposing letters and the 18th Century invention of Charles Babbage of his `analytical engine` – the mechanical forerunner of the computer.
Codes had been used during WW1 but in its aftermath most countries thought such another war was unlikely and thus did not develop cryptology further. However, with the rise of Hitler and the Nazi party in 1933 entering a military phase, Germany started to consider military code systems and concentrated on the “Enigma” machine.
The standard machine had three rotors. These three could be put in six different ways and with each having 26 letters on them it gave a permutation of 26x26x26= 17,576 different starting combinations. By introducing two `spare` rotors to allow three to be chosen from five, it increased the range tenfold and additionally at the bottom of the machine was a plug board to cross- connect ten pairs of letters by circuit wires. This gave a staggering 158 million, million, million permutations.
In 1938, with war looking more imminent, the British Government Code and Cypher School in London, under Alastair Denniston, were hoping to expand and looking for a safe site in the country. At this time the Bletchley Estate became available, a site roughly mid-way between Oxford and Cambridge, where mathematicians could be recruited. The owner, Sir Herbert Samuel Leon, a wealthy financier had already died and upon the death of his wife, Lady Fanny, in 1937 the property came on the market. A developer Captain Hubert Faulkner was about to have the place demolished and sell the land for housing, but Dennison, under the guise as part of “Captain Ridley`s Shooting Party” looked over the place and the house and several acres were bought. It was to become known as Station X. (In a prior auction for Lot 1 of the Lodge, the House, with 26 bedrooms and 43 acres, the sale was withdrawn at £7,500 –for failing to reach its reserve price.) The code name for the whole deciphering project was “Ultra”.
The Enigma machine had been invented by a Berlin engineer Dr Arthur Scherbus who had exhibited it at a Postal Congress in 1923 but it had not become the commercial success he hoped for by private and banking firms. However it was adopted by the German Government in 1926 for use by the Navy who gradually improved upon it.
In July 1939 at the Polish Intelligence Centre, south of Warsaw, the Poles divulged their success in breaking the Enigma cypher system and handed over to the British and French the methods, drawings and devices of the latest military version.
Alan Turing was a 27 year old mathematician from Cambridge when he joined Bletchley Park as an analyst on September 4th 1939, along with about 100 others. He had a Ph D from Princeton, for his work on algorithms by the use of Turing machines that he had invented. He, along with Gordon Welchman invented the Bombe machine to quickly discover the rotor setting sequences by an electro-mechanical controlled by a complex system of electrical relays. The model of the machine, called `The Bombe” that we saw was designed and made by Tony Sale.
From mid 1942 the German High Command wanted a more secure method of transmitting messages so they brought out an attachment to the Lorenz SZ teleprinter which used paper tape messages sent by wireless telegraphy. The machine had twelve rotors to scramble the letters, in lieu of six in the Enigma.
Mathematician Max Newman, and his team, was given the task of solving how to read the Lorenz messages. They worked on several machines which they called “Heath Robinsons” who were required to read, for comparison purposes, two paper tapes running at 2,000 characters per second (ie .at 30mph) along with electronic logic circuitry. Apart from frequent breaks in the tapes and the difficulty of their synchronisation there was the slowness of the electro-mechanical relays.
Newman called on Tommy Flowers of the GPO, in early 1943 to assist in the design of a machine and against all advice from others, Flowers insisted that thermionic valves (vacuum tubes –like large light bulbs) be used. Provided they were not switched on and off they were reliable – so the plan was to keep them continually on.
Flowers made a machine, named the Colossus and it was delivered to BP by January 1944 using a total of 2,000 valves – the first digital information-processing machine of which 10 were erected at Bletchley. They performed well and were in use before D-Day so that the Allies knew that the Germans had stationed tanks at the Pas de Calais rather than in Normandy. A modern version of the Colossus, using transistors, made by Tony Sale, was shown to us by our guide, John.
Just before we left the Colossus hut I was able to obtain a photo of Tony Sale who had been pottering about behind the machine during the talk. He is worth looking up on the web for further information about the Colossus, the Bletchley Park rebuild and Computing in general.
Our guide gave us a brief outline of the unfortunate ending to the life of Alan Turing. In reporting a break-in to his house to the police he mentioned the name of a homosexual with whom he had had a sexual relationship. Being illegal at that time he was charged with indecency. On 8th June 1954 Turing’s cleaner found him dead; he had died the previous day of cyanide poising – believed to have been delivered in an apple. On 10th September 2009 Prime Minister Gordon Brown apologised for the treatment that Turing had received and described it as `appalling` and said; we`re sorry, you deserved so much better.
Following this talk we visited the Museum where apart from numerous Enigma machines, a `Bombe` and pieces of `Colossus`, there was a statue of Turing, by Stephen Kettle, made of numerous stacked slate sheets. We had a brief chance to buy books and souvenirs before tea and a muffin, and then back on the coach to return by 5.30pm at Epsom. A vote of thanks was given to our organiser, John Mills.
Deric Tonge
Our guide for the day, John Miller
Statue of Alan Turing, by Stephen Kettle, made of numerous stacked slate sheets.
Alan Turing was a 27 year old mathematician from Cambridge when he joined Bletchley Park as an analyst on September 4th 1939, along with about 100 others. He had a Ph D from Princeton, for his work on algorithms by the use of Turing machines that he had invented. He, along with Gordon Welchman invented the Bombe machine to quickly discover the rotor setting sequences by an electro-mechanical controlled by a complex system of electrical relays. The model of the machine, called `The Bombe” (above and below) that we saw was designed and made by Tony Sale.
The Enigma machine had been invented by a Berlin engineer Dr Arthur Scherbus
Mathematician Max Newman, and his team, was given the task of solving how to read the Lorenz messages.
A modern version of the Colossus, using transistors, made by Tony Sale, was shown to us by our guide, John.
Tony Sale
A vote of thanks was given to our organiser, John Mills
Photographs with thanks to Deric Tonge