Tunny Gallery
Tunny Gallery
The Tunny Gallery was officially opened on 26th May 2011.

The Gallery is a wonderful recreation of a morse radio receiving station, with teleprinters, leading on to the Tunny rebuild and finally to 'Heath Robinson' (an early Colossus).

Photo: Tunny display gallery in H Block © LSA June 2012.
| EXIT | Radio Intercept  | Tunny Rebuild | Heath Robinson | Photo Gallery |


The new gallery gives an authentic look and feel as to how the equipment would have worked in an operational setting.

The Tunny Gallery, along with the Colossus Gallery, shows the entire World War II code-breaking process of the Lorenz-encrypted messages (known as Tunny in the UK) from signal intercept at the Knockholt receiving station in Kent to the production of the final decrypts on Tunny machines in Bletchley Park.


As described in videos by John Whetter

One of the German point-to-point (encrypted) radio links between Athens and Vienna used 5 character teleprinter code. This message link was nick-named 'Tunny' by the British interception Y-Station at Knockholt in Kent.

The received signal was fed into an undulator (pen recorder). The printed output was then typed by a Wren, letter by letter, onto a teleprinter which produced a standard paper tape, which in turn could be read by Heath Robinson (or later Colossus).

The Tunny machine mimics the workings of a German Lorenz from which the encrypted messages were generated. The steps in code breaking were:

  • First need to know the wheel start positions of the original Lorenz message.
  • Teleprinter tape loaded onto Colossus which is a switched program machine.
  • Manual crib used for initial switch settings on Colossus. Score built up on Colossus until max probability of correct wheel settings, then solution printed off on 'Colossus typewriter'.
  • Settings then plugged up on Tunny and machine intialised.
  • Teleprinter tape fed into Tunny tape reader.
  • Tunny produces solution.
  • Final decrypted message output on Tunny teleprinter.
Radio Intercept Station  
Radio Intercept Station
The Radio Intercept Station (with teleprinters) demonstates how the signals would have been received.

Photo: Radio Intercept Station © LSA June 2012.
Tunny Rebuild
Tunny Rebuild
After many years wait, the Tunny Rebuild was completed in 2011, and now forms a unique part of the Gallery display, and tells a vital part of the code-breaking story.

Photo: Tunny Rebuild © LSA June 2012.
Heath Robinson  
Heath Robinson
In June 1943 the 'Heath Robinson' was the first computer used in the breaking of the Lorenz codes. It was soon developed into the much more powerful Colossus.

Photo: Heath Robinson © LSA Oct 2012.
Photo Gallery  
Photo Gallery
A series of photos of all machines in the Tunny Gallery display.

Photos: Tunny Gallery © LSA 2007 to 2015.
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