138 | 13 INTRODUCING BANBURISmUS
used in Hut 8, but Hut 6’s operations did not involve ‘punching’ and ‘shoving’. It thus seems
likely that many of the other working papers as well as the Banburies themselves were related to
Naval and not to Army and Air Force Enigma, and that the Hut 8 cryptanalysts lent to Hut 6 in
April 1940 had continued to do some Naval Enigma work as well.
Using the Banburies
Alexander’s history describes how Banburies were used:^12
If the message was say 182 letters long and the text began IXBNR . . . the girl would take a 200
long Banbury and would mark in red the letters in successive columns. Having done this she
would take the Banbury to a hand punch and punch out the marked letters.
The ‘hand punch’ must have had some degree of sophistication (perhaps guide rails?) to pro-
duce the accuracy of centring of the holes. And later:
Suppose we had [message indicators] ASL and ASJ for instance. Then Banburies ASL and ASJ
would be taken out and put down on a dark background with, say, ASL underneath and ASJ on
top. The ‘guide hole’ of ASJ would be put over the 1, 2, 3 . . . 25 of ASL successively . . . . The
repeats at each position were immediately seen because a repeat implied a hole in each Banbury
at the same place and the dark background could then be seen standing out against the white of
the sheets. The scores at each position were recorded . . . .
Figures elsewhere in Alexander’s history illustrate the scale of this operation. In
Banburismus’s heyday, and in round figures, 400 messages a day averaging 150 letters each
required some 60,000 holes to be punched in a day—that is, 42 each minute, or two every
three seconds, around the clock. Of the 80,000 pairs derived from the 400 messages, about 1
in 676 (that is, 120 pairs) would have their first two indicator letters in common and be sent
to be compared, each comparison at 50 different alignments. Thus the comparisons had to
be made—and repeats counted and recorded—6000 times in a day: four times every minute
around the clock.
Early in 1941 Eileen ‘Copper’ Plowman joined Bletchley Park as a Foreign Office civilian,
aged 18 and quite homesick. She recalls:^13
My first job in Hut 8 was looking for matches in the Banburies. We worked in a group, not in
silence but not particularly chattily either: it was quite sombre. The Banburies came to us with
the holes already punched. We could sit to slide and count the shorter ones, but had to stand up
to manage the longer ones. This was definitely the most boring job that I did at Bletchley Park.
It was tedious, my eyes hurt and it was difficult for us to see the point of what we were doing.
Christine Ogilvie-Forbes also joined as a Foreign Office civilian and was posted to Hut 8 in July
- She describes working on Banburies:^14
You took a Banbury, a piece of paper 10 ̋ × 24 ̋ or longer for longer messages, printed with
vertical alphabets. Next you took a coded message, wrote its number and three-letter setting
(gleaned from the first two and last two groups). Then you pushed a ruler along the Banbury,
pencil-marking a letter in each column from the message, no gaps. Another table had a little