Thank you. The British managed to add 5-6 Attacker class escort carriers by the summer of 1943. I Imagine that had Luftwaffe presence been stronger in the Northern Waters more carriers would have been assigned to escort the convoys. There was no real reason for the convoys in good weather (summer) to venture with range of land based fighters leaving the Luftwaffe bombers on their own.
The planned convoy to Russia for Aug 1942 was cancelled due to the need to send the Nelson, Rodney, Victorious and supporting cruisers Manchester, Kenya and Nigeria and destroyers to the Med as escort for Operation Pedestal to run a convoy to Malta. Then after PQ18 in Sept 1942 there was another halt until Dec 1942 due to Operation Torch tying up large parts of the Home Fleet.
In 1943, convoys to Russia ran until mid-March, with only Dasher being involved in JW53, and did not start again until Nov. This was due once again to operations being planned for the Med (Operation Husky to invade Sicily in July and Operation Avalanche to invade Italy in Sept). Again part of the Home Fleet was sent south. Amongst the ships sent to the Med in July/Aug 1943 were the first 4 Bogue class escort carriers for the RN (Attacker, Battler, Hunter & Stalker) to form part of Force V off Salerno.
So other than early half hangar Biter & Archer and initial voyages from the USA to U.K., it was Sept / Oct before more escort carriers were able to become operational on the Atlantic and Arctic convoy routes. Their entry to service was delayed by the need to refit them in the U.K. on arrival to make them more survivable in the light of the loss of Avenger during Operation Torch and Dasher in March 1943 from an internal explosion.
From JW57 in Feb 1944 escort carriers were regularly provided as part of the escort for the Arctic convoys. But they were again suspended between the beginning of May and mid-Aug due to the needs of Operation Overlord, which utilised many Home Fleet destroyers And Western Approaches escort groups to ensure its success.
After PQ18 and the replacement of its losses, Luftwaffe anti-shipping operations, and the units involved therein, were moved from Norway to the Med. It was later in 1944 before they returned in any numbers.