Heath Robinson was delivered to Bletchley Park in June 1943 and was first installed
in Hut 11 which had been the original Bombe room for Turing Bombes, the machines
used to break Enigma.
Harry Fensom and Alan Bruce were the two GPO maintenance engineers assigned
to Heath Robinson. Two WRNS(Womens Royal Naval Service) ladies at a time were
the operators and Jack Good and Donald Michie were the code breakers.
The first problem was teleprinter tape preparation. At least 2000 characters of cipher
text was required, joined end to end to make a continuous loop. Then a similar
length of Chi wheel patterns had to be punched up and arranged to be just one
character longer than the cipher tape. This was to automatically change the relative
wheel patterns by one position after each complete run through the tapes.
Then it was found that the optical readers in the Bedstead gave errors if a long
stretch of adjacent holes or no holes occurred on the tapes. This meant adjustments
to both texts to compensate for this.
A major problem was keeping the two tapes in synchronism at over 1000 characters
per second. Originally the sprocket drive cogs were motorised but this proved
impossible to sustain without tearing the tapes and a friction drive was used from the
paper tape pulleys with the sprocket shaft just idling to keep synchronisation. This
proved to be better but there was still a problem with tape stretching in the distance
between the sprocket cogs and the optical reader aperture.
But Heath Robinson was the first machine to be used to assist in breaking Lorenz
and despite all its problems and limitations it worked well enough to more clearly
define the specification of an improved machine and this led to Colossus, but that's
another story.