DOLLIS HILL'S FINEST
See Also: COMPUTERS The Post Office Research Station; THE SECOND WORLD WAR
The
Government Code & Cypher School had been founded following the First World
War. It had been created through the
merger of the Army and the Navy's code-breaking sections. At the suggestion of the 1st Marquis Curzon,
the new entity had been placed under the supervision of the Foreign
Office. Following the outbreak of the
Second World War, it was expanded rapidly.
Many of its new staff were seconded academics. They brought to it an array of new analytical
techniques. Its activities were carried
out principally at Bletchley Park in Buckinghamshire.
The
code that the German Army used to transmit radio messages from one teleprinter
to another was dubbed Tunny by the Bletchley code-breakers. In 1941 a German soldier made the mistake of
retransmitting a message that he had just sent.
This provided a chink in the cypher's armour. The cryptanalyst John Tiltman proved to be
able to crack it. However, the prolonged
nature of his doing so by hand meant that only a miniscule portion of the
intercepted communications traffic could be understood.
The
mathematician Max Newman argued that the process could be automated. He set down a specification for a machine to
do so. At the time, the Post Office ran
Britain's telephone network. The
expertise of its research station in Dollis Hill was called upon. The engineer Frank Morrell led the
construction of an eccentric-looking, switch-based device. Those who contributed ideas towards its
creation included his colleague Tommy Flowers and Charles Eryl Wynn-Williams of
the Telecommunications Research Establishment.
The wrens who operated the apparatus dubbed it Heath Robinson in
honour of the illustrator W. Heath Robinson, who specialised in drawing
elaborate, imaginary machines. However,
the volume of coded material was so great that it was unable to keep abreast of
it.
Through
needing a decoding machine to help break the Enigma cypher, Turing had come to
know Flowers. He recommended to Newman
that the man should be invited to address the problem. The engineer concluded that there was scope
for building a piece of equipment that utilised thermionic valves (vacuum
tubes). He had used them to create the
repeaters that were central to the operation of the Post Office's telephone
system and he knew that they were reliable just so long as they were kept
switched on permanently.
The
components for the 1500-valve prototype were built and assembled at Dollis
Hill. The parts were taken to Bletchley,
where the machine was constructed at the end of the year. It was able to use binary logic to do huge
calculations. The device had no internal
memory. Therefore, it had to be
reprogrammed for each run. Its large
size led to it being called Colossus.
The device sped up the deciphering of the Lorenz code from days to
minutes.
The
2400-valve Colossus Mark II started running in mid-1944. By the end of the war there were eleven
machines in operation. Following the
return of peace, the School was renamed Government Communications (G.C.H.Q.)
and vacated its Bletchley site. Two of
the devices accompanied it. Churchill
ordered that the other nine should be destroyed along with the plans that had
been used to build them. The Cheltenham
pair are believed to have been operated until 1958. They are thought to have then been dismantled.
Tony
Sale had a working life that was largely focused upon computers. For a period, he was employed by Marconi at
its Great Baddow research laboratories in Chelmsford. There, his boss was one Peter Wright. The latter was recruited by M.I.5 to work on
radio interception and the placement of bugging devices. Mr Sale followed him into the service. Within it, he became a principal scientific
officer.
In the
early 1990s Mr Sale was running the Science Museum's Computer Restoration
Project. He saw a set of eight wartime
photographs of a Colossus. Although this
was all the evidence that was then available to him, he became convinced that
he could build a version of the machine.
Top-level security clearance was conferred upon him. He then embarked upon a programme of
interviewing the surviving project engineers.
Their number included Flowers.
One of them had a notebook that contained ten fragments of a circuit
diagram.
The
curator's task benefitted from the fact that the machines had been assembled in
large part from the standard telephone exchange gear that had been at hand at
Dollis Hill. In the 1990s the United
Kingdom's telecommunications infrastructure was being updated. Therefore, he was able to purchase many of
the components as scrap. The United
States Freedom of Information Act allowed a major breakthrough to occur in
1995. The measure enabled a technical
description of Colossus to be unearthed.
This had been written in the 1940s by a visiting American scientist.
Sale
founded the National Museum of Computing, which is based in Bletchley
Park. In 2007 it became the home of his
recreated Colossus. When this was run
for the first time, it proved to be able to crack a message that had been
encrypted in the Lorenz cypher.
Location:
The Science Museum, Exhibition Road, SW7 2DD (red, turquoise)
Chartwell
Court, Dollis Hill, 151 Brook Road, Dollis Hill, NW2 7DW
Website:
http://bletchleypark.org.uk (Bletchley Park Trust) www.computerconservationsociety.org (The Computer Conservation Society)
www.tnmoc.org (The
National Museum of Computing) https://collection.sciencemuseumgroup.org.uk/collection/cp38152/post-office-engineering-research-station (The Science Museum)
David
Backhouse 2024