Wokka me old meister, you must be naught but a lad. In the old old days, you were streamed F/W or R at Brize at the end of Ivan T Seamus O'Burns' Loadie course. (Gilthrax 's if you want the official line).
After the colostomy bags went to shiny 10, and the knuckle draggers to Lyneham-on-the-hill, the top perfomers were streamed again after Strawbs. Slow deliberate types to Wessex, and handsome, confident debonair types to starships. There were no Chin hooks.
Well that's how I remember getting to Pumas anyhow!
CG