A Warrant Officer is not promoted into the rank, he or she is appointed to it by the monarch via a Royal Warrant (mentioned earlier). That sets him aside from any other enlisted airman or woman. With the appointment goes the priviledge of being addressed by subordinates as, 'Sir' or 'Ma'am'. Who actualy calls whom what is a matter steeped in history and tradition I should have thought!
& then you get SWO's.....