In Britain, military planners took interest in the Argosy and released a new specification for a militarised variant, designated "AW.660". First flown on 4 March 1961, this model featured double the range of the "Series 100" and otherwise differed by an alternative door arrangement, which was largely to facilitate paratroop operations. Furthermore, an improved civil variant, the "Series 200", was introduced at the behest of airline British European Airways (BEA). First flown on 11 March 1964, this model featured a new wing incorporating a fail safe structure, being stronger and lighter than its original counterpart. The Argosy was operated by both the Royal Air Force (RAF) and various civil operators across the globe for numerous years. The type was withdrawn from RAF service during 1978, while the last Argosy was retired from civil operations during 1991.