When I first started my (civilian) career, a senior colleague who had seen serious action in WW II. Told me that straight after the war, when he was in my position, he had a senior colleague who, even when booking into a country pub, used his WW I military rank - "Wagstaff's the name; Captain". He also tried to pull that rank, but was swiftly put down both by his juniors, most of whom had fought in WW II, and his boss, who had been a fighting Brigadier then.
The Brigadier was always known as "The Brig."