▁terms . ▁He ▁completed ▁four ▁years ▁of ▁military ▁service ▁in ▁the ▁Int elligence ▁Corps ▁and ▁Com b ined ▁Forces ▁Entertainment ▁Unit , ▁during ▁which ▁time ▁he ▁started ▁to ▁write ▁short ▁stories . ▁After ▁comple ting ▁his ▁military ▁service ▁in ▁ 1 9 4 8 , ▁following ▁British ▁Equ ity ▁rules , ▁he ▁was ▁obliged ▁to ▁change ▁his ▁name ▁to ▁avoid ▁confusion ▁with ▁actor ▁John ▁Clark . ▁For bes ▁began ▁to ▁act , ▁appearing ▁on ▁stage ▁and ▁playing ▁numerous ▁supporting ▁roles ▁in ▁British ▁films , ▁in ▁particular ▁An ▁Ins pect or ▁C alls ▁( 1 9 5 4 ) ▁and ▁The ▁Cold itz ▁Story ▁( 1 9 5 5 ). ▁ ▁He ▁published ▁a ▁short ▁story ▁collection ▁in ▁the ▁early ▁ 1 9 5 0 s , ▁which ▁induced ▁producer ▁" C ub by " ▁Bro cc oli ▁to ▁offer ▁him ▁screen writing ▁work ▁on ▁The ▁Black ▁Knight ▁( 1 9 5 4 ). ▁He ▁received ▁his ▁first ▁credit ▁for ▁Second ▁World ▁War ▁film ▁The ▁C ock les hell ▁Hero es ▁( 1 9 5 5 ), ▁while ▁other ▁early ▁screen plays ▁include ▁I ▁Was ▁Mont y ' s ▁Double ▁( 1 9 5 8 ), ▁and ▁The ▁League ▁of ▁Gent le men ▁( 1 9 5 9 ), ▁his ▁break through . ▁Direct ed ▁by ▁Bas il ▁De arden , ▁For bes ▁also ▁star red . ▁The ▁film ▁rec ount ed ▁a ▁bank ▁he ist ▁carried ▁out ▁by ▁ex - ar my ▁officers , ▁and ▁gained ▁critical ▁success , ▁including ▁his ▁first ▁B