The attached article sets out details of the RAF Bomber Command daylight bombing campaign from the end of Aug 1944 to the end of the war.
In terms of RAF Packard Merlin Mustang squadrons, there were 7 by the end of April 1944 of which 6 were in 2nd TAF supporting the Normandy invasion. At the beginning of July, 3 squadrons were transferred to ADGB to combat the V1 with the other 3 following at the end of Sept, at which point all were moved to East Anglia as bomber escorts. From Sept onwards more squadrons began to convert to the Mustang III/IV or form on the type, at a rate of about 1 per month all the way to the end of the war in Europe as more aircraft became available. The number of operational squadrons peaked at 16 in April 1945 with a further unit in the process of converting during May.
Mustang III (P-51B/C) formed the main equipment with Mustang IV/IVa (P-51D/K) arriving on at least some of the squadrons from Jan 1945.
At the beginning of Nov 1944 1 squadron (2 from Feb 1945 following the losses suffered by the Dallachy Strike Wing on 9 Feb 'Black Friday') were sent north to Peterhead in Scotland to cover the activities of the Coastal Command Dallachy & Banff Strike Wings operating off the Norwegian Coast which were meeting increasing aerial opposition from the Luftwaffe.
Remaining Spitfire squadrons in ADGB/Fighter Command continued their bomber escort activities for the RAF as they had been doing for the USAAF 8th AF.