September 1939 and the Zealandian Admiralty sends out a set of telegraph messages to all Naval and Civil shipbuilding yards as to what they were currently building, what stocks of shipbuilding stores were on hand, and lastly what orders for further shipping were on the books. As comprehensive a listing as possible to keep the Admiralty aware of what could be built with what was available. While one of the first moves was to put the Naval yards on double shifts, this did eventually create a steel shortage in early 1941 as the steel mills had not been able to keep up with demand.
One pair of ships that the Admiralty knew about were the two Rhun class stores/seaplane carriers being built in the Grey Havens Admiralty Yards. These two 14,000 ton vessels were being built to act as mother ships to the smaller vessels. Park one of them at an island where destroyers down to MTB's could operate from made a lot of sense. But with the outbreak of war the Admiralty had the power to requisition civilian ships to provide this service in time of war. This left them with these two hulls that were perfect for conversion to what became known as escort carriers. The big 540x88 foot hull with its high freeboard was used as both a stores ship with the large loading cranes being able to load stores through both the stern opening to the hangar and by the aft elevator/lift. The forward half of the hangar being left for self defence aircraft, anti-submarine and fighters.
The ships were not large enough to operate the large Fairey Sea Battle bombers so the Fairey Swordfish that the Battles had replaced from 1939 onwards were transferred to the two Rhun class ships. Thirty-four aircraft could be squeezed into the large capacity hangar while another dozen crated aircraft could be carried as spares. The Gloster Griffon was the initial fighters aboard, but squadrons of Martlets/Wildcats, Hellcats and Corsairs could also be used and often were.
