I have to agree with Kit. The Vickers Vanguard was never operated by the RAF. It was a low wing, 4 turbo prop airliner designed to a specification by BEA for an aircraft capable of carrying 100 passengers and some freight over a distance of 1000 miles. Later, Trans Canada Airlines (TCA) expressed an interest in the Vanguard but required more freight capability over its routes. Vickers duly obliged with the Vanguard Type 951 entering BEA service in 1961 whilst the Vanguard Type 952 entered service with TCA. Toward the end of their service with BEA a number of Vanguards were modified to carry freight only and had a cargo door fitted. These were designated Merchantman. With the formation of British Airways, combining BEA and BOAC, the Vanguard was phased out of service with the remaining Vanguards and Merchantmen passing to independent airlines. The last Vanguard retired in 1996.
Perhaps the type Roy worked on at Lyneham was the Bristol Britannia, also a low wing, 4 turbo prop passenger/freight aircraft.
Anorak now removed !! Mick