I must confess to having made a point of ensuring using II(AC) and 12(B) on all paperwork when they rotated through the corner of the sandpit I called home for a large chunk of last year. In conversation I tended to use,"...Two (oxymoron) Squadron."
Roman numerals aren't just a Harrier Force thing. XV(R) Sqn is pretty much always wiritten as such, except by people who forget the (R). On a tangent, how many sqns are precious about how their number is pronounced? Six-foot are alway "Six One Seven", whereas Tremblers are "Treble One", and both get mildly vexxed if refered to otherwise, though I know not why. At least I have heard a plausible explanation for why 216 Sqn are pronounced "Two Sixteen" rather than "Two One Six" or some such; it was 16 Sqn RNAS beofre the merger with the RFC, and the 2 was added to distinguish from any former Pongo sqn.