Virtual Wartime Bletchley Park
by Tony Sale

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Tony Sale's
Codes and Ciphers

The early expansion of Bletchley Park

The initial occupation of Bletchley Park in Autumn 1938 had shown that much more accommodation space would be needed to house both GC&CS and SIS. This led to the first wooden huts being built in the grounds around the House starting in early 1939.

The shells of the Huts 1 to 5 were constructed but the Huts were not fitted out internally until it was decided who was going where when GC&CS came back to the Park in August 1939.

The Naval Section were one of the first to move, into Hut 4 alongside the south face of the House.

It was soon found that a mess room was required and Tiltman's Army Section were chucked out of Sir Herbert's dining room into Hut 5.
Dilly Knox was installed in the Cottage in the Stable Yard, together with John Jeffreys, Alan Turing and Peter Twinn. Mavis Batey(Miss Lever) was one of the first of Dilly Knox's "girls" together with Elizabeth Granger, Miss Rock and Miss Pebody.

Elmers School was requisitioned and Gordon Welchman sent there initially to do traffic analysis on the Enigma intercepts which were now coming in from the Chatham intercept station. He used coloured pencils to mark the traffic and that's how the RED key got its name.

In March 1940 the German Army/Air Force Enigma code breakers moved from the Cottage into Hut 6 which had now just been built. Work started on building Hut 8 and Turing and Twinn moved there to start on breaking German Naval Enigma.

Meanwhile the need had been seen for a separate intelligence group to handle the decrypted German texts which were coming out of first the Cottage then Hut 6. This group under Cdr Saunders moved into the first Hut 3 on what is now the Mansion car park.

But one of the ironies of early Bletchley Park was that everyone realised how vital it was that the Germans never realised that Enigma was being broken.
To try to ensure this, the English text outputs of the translated German from the Enigma decrypts were disguised as "Agent reports" to conceal the true origin of the intelligence. These first outputs went first from Bletchley Park to SIS in Broadway Buildings in London and SIS issued them under the CX/ series as Agent Reports and here is one.
The downside of this was that this initial pristine intelligence output was disregarded by the Field Commanders because they were not told of its true origin and didn't believe Agents Reports.

This page was originally created by the late Tony Sale
the original curator of the Bletchley Park Museum and is currently being hosted by Rich Sale Limited Local Search Experts.