The class is somewhat unusual as it is an amalgam of various civilian tankers chartered for naval auxiliary use and as such has included many different designs of ship.

The role of support tanker generally involves the bulk transport of fuel oils between distribution centres, the replenishment of front-line fleet tankers such as the Wave and Fort Victoria classes and using their replenishment at sea (RAS) abilities to allow them to directly support naval warships.

One of the outcomes of the 1956 Commonwealth Prime Ministers' Conference saw the Admiralty plan to improve its ability to re-supply at sea by developing a group of ships to meet their latest requirements.

[3] Appleleaf was launched as George Lyras by the Wearside shipbuilders Bartram & Sons in September 1955 and took on by the Royal Fleet Auxiliary in April 1959.

Orangeleaf was laid down in November 1953, built for The South Georgia Co Ltd as Southern Satellite and its RFA charter started in May 1959.

[5] The initial Cherryleaf was finished for Molasses & General Transport Co Ltd in 1953, as Laurelwood by James Laing & Sons.

[5] Appleleaf was launched as Hudson Cavalier was taken on by the Royal Fleet Auxiliary in February 1979, following conversion work the previous year.