Did some drivers possess a university education upon becoming drivers? If they did want to go into supervisory posts, how long would they have stayed in the position of driver?
I have never heard of a BR driver with a university education: most would have had O-Levels and, very occasionally, A-Levels, but some would have had no more than a few GCSEs, quite possibly not even that. There were, I think, two routes to supervisory jobs: either getting one of the BR management course places and doing a supervisory job as a first step before moving into management, or being an experienced member of staff who got a supervisory post on the basis of knowing the job thoroughly. Although there were exceptions, I don’t think that the second would normally lead to management. Some supervisors were relatively young, particularly in jobs that were
NOT sought after and were taken by ambitious youngsters, but others could be much older. It was not uncommon for men in their fifties to take a supervisors job once they had paid off the mortgage and felt like taking it a bit easier: the higher pay rate was offset by the loss of all sorts of enhancements.
You must understand that much of the railway saw itself as being a separate world to other industries and you learnt on the job; your worth and suitability for promotion was largely judged on how long you had been doing the job and how well your supervisors and managers reckoned you did it. At the bottom promotion was pretty well based on seniority, but above the wages grades there was more selection, but paper certificates were only a minor indicator of your worth.
There were a number of signalmen with degrees, but that was partly because it is (or was) a job that appeals to certain mentalities. You are on your own in a small room for up to twelve hours and may have no visitors.
N.b. I was a signalman, so my knowledge of drivers is just what I picked up.
EDIT: the word NOT added and highlighted.