Many a Master Pilot/Nav/Signaller/etc ended his days in the '60s and '70s in ATC - and damn' fine Controllers they were, too ! There were many Czechs and Poles among them, as I recall.
The "Four-star Brandy" system (as it was derisively dubbed) did not last long and would be long forgotten, were it not for the retention of the Master title as its last remnant.
Danny.