Was it the trainer for fiture heavy bombers pilots (Vulcan, Victor, Valiant, Canberra...) or were they selected from the fast jet pipeline?
In the early sixties all the V force co-pilots came from the fast jet stream. Varsity trainees predominately went to piston transport or, in the case of the last of the u/t sergeant pilots, to helicopters. Super transports, like the Britannia, Comet and VC10 were manned by 2nd tour co-pilots though when Bing Cross took over Transport Command there was an influx of ex Vulcan captains as instant Sqn. Ldr. captains on VC10s.