I remember the purge in the 70's to get rid of a glut of Chief techs at the time
I was one of those C/Ts. My Boss wailed, 'those with any get up and go are going!'
I left with money in the bank a pension and a good job to go to in IT aged 37.
I personally believe the glut was caused by reducing the promotion exam to just a question paper. My cpl/tech and senior/tech exam boards were far more difficult.
Re Master Pilots, my first flight was with a Master Pilot Batchelor, in a Meteor NF 11. He was a fighter pilot in WWII and I recall watching his cine film of air to air gunnery practice. It was extremely accurate and the envy of the young pilots on the Sqdn.