[1] He often described his relief when his calculations of the performance of a new braking system were tested successfully on a real steam locomotive complete with sceptical crew.
[2] During the war he worked in research establishments on numerical analysis, under experts including Douglas Hartree, and using equipment such as early mechanical differential analyzers.
Peter Hall, a Director of Ferranti and later ICL, described how Howlett did business:[2] "I explained to Jack that to order an Atlas we needed a contract that committed them to over £3m for a machine which we could not specify in performance, reliability, or delivery date.
Peter Hall invited him to take this post in 1978[2][3] and he remained editor until 1990, thereafter continuing with an active role on the editorial board until his death; he thus had the unique distinction of receiving an ICL award for 21 years' service which only started at the age of 65.
[2][4] He ran the meetings of the editorial board efficiently in the relaxed atmosphere of his London club, always followed by good food, wine, and conversation.