Under the terms of the Lend Lease agreement between the US and Britain 39 US built escort carriers were transferred to the control of the Admiralty. Of the first five escort carrier conversions completed for the RN (Archer, Avenger, Biter, Charger, and Dasher) were essentially copies of the 'Long Island' design. Charger was the first to be handed over, commissioning as HMS Charger on October 2nd 1941; however, the USN reclaimed her two days later for duty as a training carrier. The second carrier Archer was a fairly rudimentary conversation and she saw little active service before machinery problems saw her laid up for a considerable time. Avenger and Dasher were both sunk, Biter being the only one of the initial batch to see continuous active service until the end of the war.
The U-Boat treat was increasingly claiming merchant and military vessels on vital convoys; the need for more escort carriers was to become a priority. Orders were placed for two further batches of US CVEs whilst the Admiralty undertook to complete a further five. Batch 2 was 11 'Bogue' class CVEs, although some 'Casablanca' class vessels were initially earmarked for transfer, but these were diverted to the US navy. Batch 3 was a repeat order for a further 23 Bogue class vessels.
By the end of 1942 the RN had received 8 US escort carriers and completed two conversions in British shipyards. During 1943 it was to gain a further 30; 27 lend lease and 3 more British conversions. This was to be the height of escort carrier production for the RN, the final four US built vessels and the final British conversion had all arrived by the end of February 1944.