I served my time as an apprentice there from 1964 to 1969 finished up on maintenance in the main workshops .two guys in that first year had one 'o' level .One year later the intake of apprentices had 90plus 'o'levels between them.
I can remember it well from the old engine test house to the new one, the metal electroplating unit ,down by the main road,the tank testing ground going underneath the Bailey bridge.