I've just been leafing through Martin Bowman's book "Lightning Strikes Twice" he states that the C.O. of 23 Squadron at Leuchars as of 15th September 1972 was a Squadron Leader. But I don't believe any fully constituted Operational Squadrons were co'd by any other than the rank of Wing Commander by then. The rank gradually replaced Squadron Leader during the war as it was deamed worthy for commanding the new four-engined Bombers i.e. Lancaster, Halifax, Stirling and what have you! Hence Wing Commander Guy Gibson. All the B.O.B. Fighter Squadrons were led by Squadron Leaders.
FB the 1st