The Secret Digit

We describe three rather special Borehamwood digital computers in this chapter. Two of them were designed to perform tasks for the UK’s intelligence services, via GCHQ (Government Communications Headquarters). The third went to a joint British–Australian long-range missile facility in Australia, to be used in analysing data from the Woomera test range. The time frame of all three computers, from conception to delivery, covers the period 1949–1956. Internally to the Borehamwood Research Laboratory of Elliott Brothers (London) Ltd., the projects were identified by sequence numbers in the company’s list of orders.