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Graham Farmelo's review of David Edgerton's book Britain's War Machine: Weapons, Resources and Experts in the Second World War (21 April) was refreshing, as there is clearly still much to do to get a balanced view of the events of 1939-45.

However, having studied the life and work of the third of Winston Churchill's inner trio of scientists, Edward Appleton (who had control of the civilian research establishments, paralleling Henry Tizard's authority over the military ones), I can amplify two of the points that Farmelo raises.

Having spoken to some of Appleton's proteges in the past, I can confirm that Frederick Lindemann was viewed with hostility by both Appleton and Tizard and their teams, and was regarded as a significant hindrance to the war effort.

Further, Edgerton's highlighting of the British provision of a bombsight design to the Americans is somewhat misleading. This is because the cavity magnetron, the work on which had been sponsored by Appleton and which was undoubtedly a very valuable innovation (the original is now preserved in the Smithsonian Institution in Washington DC), was reluctantly provided to the US with the primary objective of exchanging it for the American Norden bombsight, which was deemed necessary to improve the effectiveness of British attacks.

Peter Excell, Glyndwr University