Bletchley Park and Codebreaking
What is understandably less well known is Birmingham’s participation in the clandestine world of code breaking via the creation of Colossus – a set of computers, arguably the world’s first programmable model, the design of which is credited to the research telephone engineer, Tommy Flowers. Colossus was pivotal in the process of breaking the Lorenz Cipher, a top level German military communications system. The Lorenz Cipher sent its messages in binary code while the more famous Enigma Code operated in Morse Code.
Colossus was operated from Bletchley Park which was the home of the Government Code & Cypher School in World War Two. The prototype was operational by December 1943 and in place at Bletchley by June 1944. Ten Colossi were in use by the end of the war. More is now widely known about the contribution to the war effort made at Bletchley Park, most famously associated with the pioneering work of Alan Turing who employed the Bombe decryption device rather than Colossus in his work. Two popular films – Enigma (2001) and The Imitation Game (2014) have brought this story to wider public attention – events which well into the latter half of the twentieth century remained highly classified government information. The existence of the machines was kept secret until the 1970s with design plans disposed of in the 1960s.
My interest in Colossus and the role Birmingham played in its construction was initially whetted by an article I strayed across many moons ago now on the Birmingham Live website which was first published in 2008. The piece focused on the GPO (General Post Office) and BT (British Telecom) factory on Fordrough Lane, Bordesley Green. The GPO was a major employer in Birmingham having three plants in operation and employing well over 2,000 people by the 1930s. The plants were at the Jubilee Works in Sherlock Street, Garrison Lane and Fordrough Lane. An act of 1912 gave the GPO a near complete monopoly on the provision of telephone services which meant the business required warehousing and transport sites throughout the country and Bordesley Green was selected as one of the three national sites due to its close proximity to the railway network.
A local researcher and author, Ken Govier had uncovered documentation relating to the contribution made by workers at the Fordrough Lane factory to creating parts for Colossus. Ken was on the brink of publishing a book on the history of the Post Office/ BT factories in the UK – I’m not entirely sure if the book was published although the library does retain copies of other texts written by Ken. The claim was made that security on the work carried out at the factory was so top secret that many of the workers had no idea they were making parts for Colossus.
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Interestingly, the Fordrough Lane factory had a test site and chemical laboratory in operation from around 1925. The initial purpose of the lab was to provide expert testing facilities to assist with the purchasing of engineering goods. Who knows – these labs could have been employed to test parts made for the Colossus but that may be mere conjecture and speculation on my part. By 1939, 25 personnel were working in the laboratory so quite a sizeable operation.
Please contact archives.appointments@birmingham.gov.uk if you are interested in viewing the contents of MS 2615 as your request will be passed to a third party for permission to view the collection.
Paul Taylor, Coordinator
This post was updated on 09/02/2024 in response to information about the role of the Colossus.
The Iron Room 
The untold story of The GPO’s Colossus computer of Fordrough Road in Bordesley Green in Birmingham which played a role in Alan Turing’s efforts to break the German Enigma code during World War Two. I believe that #Birmingham City Council’s Museum’s Collection Centre in Nechells holds a version of Charles Babbage’s original algorithm machine which was the first functioning computer