Welchman died in 1985; his final conclusions and corrections to the story of wartime code breaking were published posthumously in 1986 in the paper 'From Polish Bomba to British Bombe: the birth of Ultra' in "Intelligence &amp; National Security", Vol 1, No l. The entire paper was included in the revised edition of "The Hut Six Story" published in 1997 by M &amp; M Baldwin.