SImPSON | 135
At first the placing of messages correctly in depth by counting the repeats between them
was probably done by writing pairs of messages—selected as having their first two indicating
letters in common, as already mentioned—on two strips of paper and sliding these against
each other. This simple approach was quickly elaborated and a technique was developed
that served with distinction until September 1943. The technique used long sheets of paper
on which vertical alphabets were printed: variously with 60, 120, 180, or 260 columns. With
rows and columns both spaced at 5 mm intervals, each letter occupied a 5 mm square. The
longest sheet, the 260-column version, was therefore about 1.3 m long (plus margins). When
two of these sheets were at their extreme end of comparison, they would extend to nearly
2.6 metres.
The sheets, printed in Banbury, were whimsically called ‘Banburies’. Using them might have
been called ‘Banburism’, but the German form Banburismus was preferred: this was the humour
of J. B. Morton (‘Beachcomber’) whose articles in the Daily Express had a devoted readership
for 50 years before, after, and (more importantly) during the war. One of his recurring charac-
ters was ‘Dr Strabismus (whom God preserve) of Utrecht’.
The Banburies carried the reference ‘OUP Form No 2’, so the Banbury printer was presum-
ably a subcontractor of the Oxford University Press. Bletchley Park ordered them through
Paymaster Commander Edward Hok, the head of the printing and code production unit at
Mansfield College, Oxford; for example, they ordered 7000 of various lengths on 13 January
- The National Archives at Kew have a pristine Banbury, shown in Fig. 13.1. This seemed as
close as we were going to get to Banburies but there was a surprise to come.
Banburies in the roof
In 2013 a bizarre turn of events catapulted some ancient Banburies into the modern world.
During the restoration of Hut 6 at Bletchley Park, a workman found some scrunched-up papers
stuffed into the roof. The plausible surmise was that someone had used waste paper to fill a hole
and keep out the draught. Fortunately the papers were not discarded, and they turned out to be
cryptanalysts’ workings, including two used Banburies (Figs. 13.2 and 13.3). No one had seen a
used Banbury since Bletchley Park packed up at the end of the war.
Another two of the papers had helpfully written on them ‘Yellow’ and (respectively) ‘April
14’ and ‘15/4/40’. ‘Yellow’ was Hut 6’s shorthand designation for the particular Enigma network
used by both the German Army and Air Force during the invasion of Denmark and Norway,
launched on 9 April 1940. Hut 6 broke Yellow on 14 April. The relics in the roof are a direct
connection back to that historic day.
Both Banburies are incomplete. They differ in several respects from the (presumably) later
version held by the National Archives. The roof relics have lettering that is more ornate, no
‘OUP Form No 2’ and no recurring alphabet along the base. The holes punched in them by
their unknown users are vividly clear, each hole centred with impressive accuracy on one letter
in each of successive columns. It was not always so. Bletchley Park complained to Commander
Hok on 30 December 1941 that:
The printing of the last batch of OUP Forms No 2 . . . is somewhat irregular and the variation
in the amount of space between columns is at times sufficiently great for the forms to give the
wrong answer.