Virtual Bletchley Park Now
by Tony Sale

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Tony Sale's
Codes and Ciphers


The Rebuild of the Turing/Welchman Bombe

The possibility of re-building a Bombe was discussed very early on by Tony Sale and the Committee of the Computer Conservation Society. It began to become a realistic possibility when a set of drawings of the wartime Bombe and some reports were released to Tony Sale by GCHQ in 1995. These drawings were all of piece parts for the Bombe with no assembly drawings and John Harper recently retired from the computer company ICL agreed to have a look at them and start a "gathering of information" phase including locating and talking to engineers who worked at the British Tabulating Machine company (BTM) at Letchworth, where the Bombes were made.

This received a big impetus from a "Punched Card Reunion" of ex ICL staff in October 1996 which John Harper addressed and from which he received many offers of support.

A crucial factor was the discovery in November 1996 by Tony and Margaret Sale in the American National Archive of the 1944 US 6812 Army Division report on the Bombe.

This report gave a detailed account of the setting up, running and maintenance of the Bombes being run by American service men in a wing at Eastcote in North London. It also included test menus and a large set of photographs.

So now it was possible to see how all the piece part drawings might go together and a rebuild became a possibility.

Tony Sale had already made contact with Quantel Ltd, a computer graphics company, for support for the rebuild of the Colossus computer. They were enthusiastic about a Bombe rebuild and agreed to provide start-up funds for it.

The Computer Conservation Society agreed to host the Bombe rebuild so that it could benefit from the British Computer Society's Charitable status and a bank account was opened on 10th February 1997 and the Bombe Rebuild Project came into being.

The Bletchley Park Trust agreed to make available Hut 11, the original Bombe room in Bletchley Park, provided that the Bombe Rebuild Project re-furbished it, which it did, at a cost of 5,000 pounds sterling and set up a workshop area.

It was agreed that Tony Sale and an assistant would try to build a checking machine as a first step. This would allow some rebuild techniques to be tried out on a small scale prior to a complete Bombe rebuild.

During 1997 John Harper and his band of volunteers transferred the GCHQ drawings to CAD and overall assembly drawings were re-created. John Harper was helped in this by resources being made available from the Northern Telegraph Company (NORTEL) who had direct links to the original BTM company. In 1998, NORTEL's Technical Director, Alan Fox, presented the Project with a further cash donation to cover the mounting costs of machining parts for the Bombe.

Many of the WRNS who operated the Bombes during the War made donations to the Bombe Project which were gratefully received.

When, in 1999, Tony Sale was no longer Museums Director the Bletchley Park end of the project was wound down and John Harper took over the project.

The results of his labours can be seen on his web site and a considerable part of the Bombe should soon be on display in Hut 11 in Bletchley Park.

This page was originally created by the late Tony Sale
the original curator of the Bletchley Park Museum