A Top Secret Machine That Solved An Enigma

Wednesday, 01 September 2010
Bletchley Park Guide John Jackson Looks At The Project To Rebuild The Bombe, The Machine Used To Break Wartime German Enigma-Enciphered Messages

Britain’s greatest secret of the Second World War – its codebreaking headquarters at Bletchley Park near Milton Keynes – remained on the most highly classified list, known among only a handful in the corridors of power as TOP SECRET ULTRA – until 30 years after the war.

Among Bletchley Park’s most ingenious hush-hush wartime inventions was an amazing electro-mechanical machine called the ‘bombe’, which was used to break secret messages transmitted on the German Enigma cipher machine, which allowed the Allies to read the most important secrets of the Third Reich.

Developed by Cambridge mathematicians Alan Turing and Gordon Welchman, the bombe broke some two and a half million Enigma messages during the war and historians have said Bletchley Park probably shortened the conflict by two years.

But, at the end of the war, everything at Bletchley Park was ordered to be destroyed to ensure that the secret work carried out by the Government Code and Cypher School (GC&CS) – now called GCHQ – was maintained. All 211 Bombes built by the British Tabulating Machine Company (BTM) at Letchworth in Hertfordshire were broken up. Of the 145 bombes built by the Americans, one still exists and is on display at the National Cryptologic Museum in Maryland.

But, in 2007, the whirring sound of the bombe was heard again, more than fifty years after they had been silenced by peace in Europe, following a twelve-year project to rebuild the machine by a group of dedicated engineers led by Bedfordshire Freemason, John Harper. His team had to look through around 4,000 documents handed to Bletchley Park by GCHQ. In July 2007 the bombe rebuild was officially opened by Bletchley Park Trust Chief Patron, the Duke of Kent.

Now, the bombe is run for the benefit of visitors. Using wartime Enigma-encyphered messages, the rebuilt bombe can today find the original settings of the German operators in around eleven minutes.

When Bletchley Park (BP) was faced with redevelopment as a housing estate in the 1990s, the local historical society stepped in to save it as part of Britain’s national heritage and it opened to the public in 1993, the year in which local masons came together to form Bletchley Park Lodge, No. 9518. Two lodge members play key voluntary roles at ‘BP’, including John Chapman, who runs the Post Office – one of the top ten in Britain for First Day Covers – and Brian Mead, one of the duty managers. Two volunteer guides, Nick Miers and John Jackson, are also masons.

Another masonic connection to the historic site is Hubert Faulkner, who bought Bletchley Park in 1937 when the part of what became the codebreaking section – Lot 1, comprising the mansion (now a Grade II Listed building) and fifty-five acres of land – failed to reach its reserve price of £7,500!

However, Faulkner subsequently sold it on to Admiral Hugh Sinclair, head of the Secret Intelligence Service (MI6), who had overall responsibility for GC&CS. Faulkner’s building company erected the famous huts which housed the codebreakers.

Faulkner was an active Freemason during the war and from April 1942 until February 1945 was Master of Cowper and Newton Lodge, No. 2244, which meets at Olney in Buckinghamshire. In May 1946 he became a founder member of Cowper and Newton Chapter.

Bombe rebuild project leader John Harper, a Lewis, comes from a line of masons. Initiated in Old Cedarians Lodge, No. 8078, Province of Bedfordshire, in 1987, of which he was Master in 1999. He explains:

‘I did not come into Freemasonry until I felt that I could give the time it deserved. I had to travel a lot during my early career. This was a disappointment to my father, as he had died by the time I was invited to join my old grammar school lodge.’

Initially his father was a Middlesex mason but found when he moved to Buckinghamshire that attending Brent Valley Lodge, No. 3940, was difficult, so he joined Wineslei Lodge, No. 2435, in Winslow and Cheiron Lodge, No. 7775, in Aylesbury. John Harper’s grandfather was also a Middlesex mason as were his uncle, godfather and a cousin who is a current Leicestershire mason.

Reconstructing the Bombe
About the bombe rebuild project, Harper explains: ‘I worked for ICL at Stevenage, the successor to British Tabulating Machines (BTM). I had heard of a project built by BTM during the war which was hush-hush. Eventually the secret came out in the 1970s and I was fortunate in being able to recruit expert volunteers.

‘The research began in 1996 after GCHQ returned the drawings to Bletchley Park, and in September 1997 we delivered the first part of the frame, the final section being completed three years later. By April 2002, all the moving parts were active under DC power.

‘By April 2006, the construction was finished except for a complete set of drums, which replicate the rotors on an Enigma machine. That year we also completed a rebuild of the checking machine, which took the information from the bombe to see if it had come to a correct decision. We also had a Typex machine – the British cipher machine, some of which were specially modified during the war to replicate the workings of the Enigma machine – to actually decipher the original German message.’

Both the rebuilt checking machine and the modified Typex – along with an Enigma machine – can be seen alongside the one-ton bombe rebuild at Bletchley Park. The rebuild project finally saw the official switching-on ceremony in September 2007 by Bletchley Park’s Chief Patron, HRH The Duke of Kent.

Working for the film, Enigma
John Harper and his team also helped the makers of the film Enigma, based on Robert Harris’s best-selling novel, by providing many specifications and drawings to enable Asylum Models and Effects to build six replica bombes, which the film-makers insisted should be as real as possible.

John Harper explains the problems that arose over the Enigma replicas: ‘The bombe rebuild team were called in rather late in the proceedings and this put us under great pressure to provide existing drawings and to produce new ones.

‘One thing that added to the pressure was that we had been carrying out our research and had been producing new drawings from the inside-out. Asylum wanted the outside drawings first so that they could make the main boxes first.’

This was a problem, as John Harper’s team had planned to leave the covers until last, as was the case with the original machines. One of these mock-ups is now also on display at Bletchley Park, while another is at the Letchworth Heritage Museum. Go to www.jharper.demon.co.uk for more information about the bombe rebuild and to www.bletchleypark.org.uk for more general information about Britain’s wartime code-breaking centre.

Sinking the Scharnhorst
In their public demonstrations the bombe operators break a real wartime message – the last signal sent from the battlecruiser Scharnhorst – which was encyphered on the ship’s Enigma machine, intercepted, transmitted to Bletchley Park, where the codebreakers provided a ‘menu’ to be run on the bombe, whose results were passed on to the checking machine. The information went to the codebreaking hut, the rest of the key found and the message deciphered using a modified Typex machine, the British equivalent of Enigma.

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