I’m grateful to my readers for some of these corrections. Simon Lavington (SL) generously read the text closely and provided me, after print publication, with a number of corrections to my facts, and some enlightening judgements. Professor Lavington’s book on the Mark I machines was published in 2019.


Figure 7 appears in John Dummelow, 1899-1949, Manchester: Metropolitan-Vickers Electrical Company Limited, 1949 as mentioned in the Figure Notes but omitted from the reference list.

Figure 43 is from a Ferranti internal report of January 1954. There is a copy in University of Manchester Special Collections NAHC/FER/C/13b.

Notes and queries

On p53 I have confused the Telecommunications Research Establishment in Malvern and the Post Office Research Station in Dollis Hill.

p54 Figure 38. The dot in William’s Figure is in Sweden, not Norway. I don’t know what installation this refers to.

The arithmetic in Figure 43 on p61 appears wrong, but only because I cropped out a line item at the top where Ferranti had also predicted £100K of commercial sales. Looking at it now, I wonder if they hit their target.

p66 The road is Nursery Avenue, not Nursery Road.

p115 Ida Fitzgerald was the lone wirewoman in the University lab, and the woman photographed is not (necessarily) doing a wirewoman’s job, but she was doing it in Ferranti. So the identification of the woman in the photograph as Fitzgerald is less than likely.

p116: Alan Turing’s secretary was S J Wagstaff (SL).

p119: There is doubt as to whether Mary Croarken had worked in Hartree’s group (SL). I have somewhat mangled the physical tasks of using the Mark I and the reader is best referred back to the original sources.

p145: In the service of a throwaway gag about two and a half machines (the third Atlas machine was not sold at anything like list price) I’ve given the poorly sourced impression that the project was a failure on its own terms, but that whether or not that it is true should not obscure its considerable technical achievements.

In Note 9, the neuron estimates were actually a million, a thousand million, and ten thousand million.

Note 38 says that the history of Noel Teulon Porter and the Half Moon Club is still to be written. After publication I came across Philip Pattenden’s article in the 2005/6 Peterhouse Annual Record, which covers most but not all of the sources I know. Thanks to the Librarian at Peterhouse College Cambridge for supplying a copy.

Over-hypen-ation and tpyos

p10 second para line 2: missing ‘been’.

p43, 7 lines from bottom: extra ‘was’.

p55 l-2 rec-ru-uited

p110 Sun-day

p128 Mis-sed

p163 second line: ‘you can’t see them both’.