Air group organisation had to change several times during WW2 to allow the FAA to cope with the ever increasing tempo of operations and the changing nature of the campaigns it was involved in. These went beyond simple adjustment of numbers on a carrier.
Pre-war there were only enough squadrons for each operational carrier. Problems arose when the RN regained control of the FAA in May 1939 and again around the outbreak of war as new squadrons were needed for a reactivated Hermes and Furious. At that point there was an aircrew shortage. Plans only saw squadrons being formed about 6 months before a parent carrier was due to complete with training being geared to that. And the FAA was then forced to base aircraft ashore to defend Scapa Flow, a responsibility that should have fallen on the RAF, and to help out Coastal Command in the southern North Sea and Channel area from 1940.
So the next plan was to try to create "supernumerary" squadrons that could reinforce carrier groups for specific operations or replace squadrons worn out by action. But such was the increased demand for aircraft as the carrier fleet expanded from late 1942 with escort carriers arriving from the USA, and the outcry from the Air Ministry over production demands, that it had to be scaled back and was never implemented as intended.
Late 1943 also saw the formation of Wings to control the multiple fighter or TBR squadrons now intended for each carrier.
With regard to that last outfit, it is reflective to a degree, of the FAA expansion plan for 1944 of providing each carrier with enough aircraft to allow it to vary the air group on board between 2 fighters per TBR and 1 fighter per TBR. So in theory there were to be, for an Illustrious class, 36 Corsairs and 27 Barracudas/Avengers allowing a 36/18 or 27/27, or anything in between, outfit to be carried as circumstances dictated. This only lasted for a short time.
Fighter squadron sizes on the Illustrious class also increased in 1943-44 period from 10 to 14 to 18.
The complement given above for June 1944 therefore represented 3 x 14 plane Corsair squadrons (1830, 1833 & 1837) plus 15 Barracudas (9 from 810 & 6 from 847). Victorious also used a similar set up at this time. So an extra squadron of fighters aboard for specific operations, at a cost of reduced TBR numbers, with the extra TBR left ashore. But in Aug/Sept 1944 a further reorganisation took place. One of the fighter squadrons for each carrier (1837 & 1838) were disbanded to allow the others to be brought up to 18 aircraft strength and give each squadron some extra pilots to cope with the expected increasing tempo of operations. At the same time the TBR Wings (of 2 squadrons) in each carrier was reduced to a single slightly enlarged squadron.
Then on 30 June 1945 the FAA was finally able to formally adopt the US style Carrier Air Group it had wanted for some time, with the intention of swapping out a whole CAG periodically, rather than replace squadrons or individual personnel in squadrons. The exact shape of each CAG was intended to be driven by the class of carrier and it's capacity, there being different compositions for the Illustrious class, Indomitable, the Implacables and the light fleet carriers. Replacement CAGs were to be provided on a one for one basis for fleet carriers and one for every two light fleets. Most of the squadrons necessary to form the 1st to 18th CAGs for the 6 armoured carriers and first 4 light fleet carriers were in existence when the war ended in Aug 1945. So the plan was well advanced.
There were then to be extra specialist squadrons for specific purposes, for example night fighters, photo Recce and long range strike (Mosquitos).
It effectively took until late 1942 / early 1943 for things to get sorted out for the FAA. Long promised modern aircraft types began to appear, and in significant numbers, aircrew training programmes were delivering plenty of new personnel etc. But 1941/42 everything was a bit hand to mouth.
