One reason for this was the machines being kept in use until the 1960s to spy on Germany, the Netherlands and the Nordic countries as their leftwing political parties and politicians were suspected of being aligned with the Soviets; and official secrecy does seem excessive but to be fair there was also a genuine element of protecting these boffins and their families as well as national populations.
World War II divided Europe and basically merged into the Cold War; and even in my youth there were some serious civil disturbances across Europe – we had the miners strike, various riots and the cops going in really heavy on hippy convoys as they couldn’t cope in any other way with their drugs culture (which was itself often blamed on “Soviet plots”; and the Soviets blamed their citizens drugs use on “Western Influence”). People were actually getting stalked and intimidated or even assasinated for their work (both in public and private sector) by a variety of groups and individuals.
What I think Britain should have done is given these boffins honours for their peacetime work – after all having working internet and telephones is as important to a country as robust defence infrastructure…
