despite its strategic industries (rail and aero-engine), derby suffered comparatively little damage in both world wars (contrast bristol and filton). this may in part have been due to the jamming against the german radio-beam navigations systems (x-verfahren and knickebein, camouflage and decoy techniques ('starfish sites') were built, mainly south of the town, e.g. out in fields near foremark (ref. kirk, felix & bartnik, 2002, see talk; see also).