There is so much to do and see at Bletchley that I’ve decided to break up my review into separate parts to keep it manageable. All the details and pictures can be found “here.”:http://wasleys.org.uk/eleanor/presocialhistory/socialhistory/social/social/bletchley_park/index.html
After Block B with information about the Enigma and Bombe machines, these are probably the two most important huts to visit. This was where information from the German Army and Navy was received and interpreted. For increased security, the two processes of decoding and interpretation were kept separate in different huts. Hut 6 received the raw data and deciphering the information. It was then passed to Hut 3 for translation and analysis.
Hut 6 was under the control of Gordon Welchman who had his office here. Raw data from the German army and air force was intercepted by Y stations and sent to Bletchley either by teleprinter or dispatch riders and came to the REGISTRATION ROOM. Messages were sorted to confirm which Enigma unit they were being sent from.
The messages were then passed to the INTERCEPTION CONTROL ROOM which checked that all networks were being covered. If one station had difficulty intercepting signals because of poor reception, another was called to provide backup. Messages were logged and cross indexed to build up a detailed picture of signals from all parts of the German forces.
Before the days of the Bombe, the messages were then sent to the METZ or PAPER STACKING ROOM to test out possible settings for that day’s Enigma keys. Holes were punched in large pieces of paper known as Metz, according to the keys in the various messages. The sheets were then stacked over a light. If the light shone up through a hole it was called a drop indicating what may be the right setting for the Typex machine.
Cribs later became very important for operating the Bombe. Operators in the CRIB ROOM looked for routine phrases like ‘weather report’. One or two messages containing a crib were then selected to be passed onto the Bombe operators in a different building.
Once the Enigma settings had been broken, the messages were sent to the DECODING ROOM. The settings on the Typex machines were adjusted to those of that day’s Enigma machines and the intercepted messages were typed into them. The decoded German messages were then passed through a small tunnel to Hut 3 for translation and evaluation. The unit was headed by Cdr Malcolm G Saunders, a naval officer, who was brought in for his intelligence background and knowledge of German.
The decoded messages from Hut 6 arrived in the DUTY OFFICERS ROOM through a makeshift tunnel. The Duty Officer sorted the messages into order of priority before passing them to the Watch.
There were four Watchkeepers in THE WATCH who were civilians fluent in German and they translated the messages into English. They used their experience to fill in any missing letters from the original transcripts.
They worked closely with army and RAF advisers in the ADVISER’S ROOM who could offer advice on military and technical details. They made sure the correct terminology was used before the messages were passed to the INTELLIGENCE ROOM. As well as assessing and evaluating the information, the Intelligence Officers needed to work out cover stories for the content so the German’s would not know their Enigma codes had been broken. The reports were given the appearance of coming from an MI6 spy codenamed Boniface, who had a network of imaginary agents across Germany.
The information was now ready to be transmitted to MI6 and a limited number of senior army and RAF personnel. The Hut had its own direct secure teleprinter line to London with a back up Typex machine in case the teleprinters broke down. Sixteen WAAF teleprint operators, four WAAF typists and four external messengers worked here.