From Wiki :
"
2TAF was formed on 1 June 1943 as HQ Tactical Air Force from Army Co-operation Command, in connection with preparations then in train to invade Europe a year later. "
"Fighter Command was split into the Air Defence of Great Britain, retaining fighter units for home defence, and No. 83 Group and No. 84 Group operating aircraft, and
No. 85 Group controlling ground-based units, for the Second Tactical Air Force."
https://en.wikipedia.org/wiki/RAF_Se...ical_Air_Force