CHAPTER 13

Introducing Banburismus

edward simpson

O

nce the bombes got going, they made a massive electromechanical attack on the

Enigma’s daily-changing key. But with limited numbers of bombes, the demand on

them had to be minimized. For the Naval Enigma, Hut 8 used a cryptanalytic pro-

cess called ‘Banburismus’ to reduce the amount of processing that the bombes had to do.

Banburismus was largely a manual process—although with a vital contribution from the card-

sorting machines in the Hollerith section—and employed a handful of the best cryptanalysts,

with a large supporting team of WRNS (‘Wrens’) and civilian ‘girls’. The startling recent discov-

ery of Banburies in the roof of Hut 6 at Bletchley Park adds a new twist to the story.

Background

There is much high drama in the story of breaking and reading Enigma:

•    the    secret  meeting of   British    and French  cryptanalysts   with    their   Polish  counterparts    

outside Warsaw in late July 1939 (see Chapter 11)

•    Colonel    Stewart Menzies (later  to   be  ‘C’,    the    head    of   the    Secret  Intelligence    Service)    

waiting at London’s Victoria Station in mid-August 1939, in evening dress and with the

Légion d’honneur rosette in his buttonhole, to receive a Polish-made replica Enigma

machine from the French Intelligence’s Gustave Bertrand

•    the    Royal   Navy’s  Anthony Fasson  and Colin   Grazier of  HMS Petard kick-restarting the

reading of U-boat Enigma in October 1942 when Hut 8 had been shut out of it for ten

months, their gallantry commemorated by posthumous George Crosses for securing

Enigma materials from the sinking U-559 at the cost of their lives

•    some   two hundred purpose­built   bombes  clicking    away    endlessly   at   Bletchley  Park    and 

its outstations (see Chapter 12).

At first sight, the quaintly named ‘Banburismus’ component of breaking Enigma offered no

high drama. Both the mathematics it was based on and the technology of its application dated

back some two hundred years to the eighteenth century. Yet the handful of cryptanalysts and

supporting ‘girls’ who employed Banburismus—building on Alan Turing’s genius and carried