After discharging from the Army, Mr McDonald briefly returned to Scotland where he worked with a law firm.
But after that career did not work out either, he left for Pakistan where he taught for a year.
On his return to the UK, his career in politics started to get underway.
He began as a civil servant, before moving up the ranks to become the Ministry of Defence spokesman during the Falklands War, when he provided televised updates as British forces recaptured the islands from Argentina.
During the three-month conflict, Mr McDonald became renowned for his restrained, and at times emotionless, style of delivery.
Archive footage by Forces News, at the time known as BFBS, shows Mr McDonald, in his typical monotone, announcing that British forces had taken Darwin in the Falklands:
"We have just learned that the 2nd Battalion of the Parachute Regiment," Mr McDonald said slowly, before he paused, and added, "has taken Darwin and Goose Green."
Mr McDonald was one of the few avenues of information throughout the conflict with reporters only able to report audio over satellite phones.