I did ask about the naming when young relative joined II (AC) Squadron and was told that it was II "because it's old" and that the "AC" stood for "Army Co-operation".
I now await confirmation of an oxymoron (although I have also been told they have a goodly collection of redundant armoured vehicles around the squadron headquarters).
(Edited to add. TMJ. Apologies for repeated use of oxymoron. I hadn't read you post).