Hi,
I spoke before about this project,it was Armstrong Whitworth
AW.66,and in Flightglobal the AW.65 after the developments
for it,and from Argosyair site;
Late in 1955 AWA came up with a design designated AW 66. This was a high wing monoplane with the tail surfaces carried on two closely spaced booms growing out upper sides of the fuselage. At the rear there was a floor level hinged door suitable for both air dropping and ground loading. It had an all up weight in the region of 65,000 lbs. and was powered by two 3,000 hp prop jets. While working on the design of the AW66, extensive market research was carried out. This indicated that there was a potential market for a similar civil aircraft. To meet the civil requirement a revised design was developed, designated AW 65. While the requirement for air dropping disappeared, the need for both front and rear ground loading through full section doors appeared.
http://www.flightglobal.com/pdfarchive/view/1958/1958-1-%20-%200616.html?search=armstrong%20AW
http://www.argosyair.co.uk/introduction.html