Another gem from the website of Tony Comer, the former GCHQ Historian, on a broad theme and very analytical: Sigint Historian: Ten avoidable problems which made the Royal Navy's encryption exploitable in 1939 he opens with: I have not looked to see if there is a similar thread here. The author's name only appears on a previous thread added this year.
Thanks for that. I recently came across this in Australian Archives, downloadable free ( 12.7 MB ). Similar story of general failure in the early 1940's re Japan. NAA: A6923, HISTORY OF SIS Series number: A6923 Control symbol: HISTORY OF SIS Barcode: 3199101 Number of pages: 64 Title: History of Signal Intelligence Service in India and South East Asia Commands 1939-1945 [1cm folios]