"......I was suprised (as a Senior Aircraftman) to be addressed by a Sergeant First Class (or so it seemed) as "Sir"....."
I would imagine that was just the young lady in question being polite and courteous towards newly-arrived guests in her country. A charming gesture.
SASless, in the RAF it is often the 'commissioned ex-rankers' rather than the straight-through baby officers who make the most smoke and noise about their new-found status in life. Real officers treat RAF WOs with the respect their status rightly merits.