I was very nearly a Sergeant Pilot. On one of my interviews with the CGI at Oakington in 1961 I was asked whether I would like to be one; it must have been something to do with my Ps & Qs. I declined the offer inferring that I would rather leave the service. They must have been short of recruits because it was never mentioned again.
IIRC when the Varsities arrived from Valley I am sure that there were two sergeant students among them. When I arrived in Borneo in January 1966 there were two sergeant pilots on the squadron; Jim Lawn and Dave Cramp; possibly the same two.
Eventually Dave Cramp did my captains qualification and line check at Sumburgh in November 1978.