At Trinity College he qualified as an electrical engineer, with an MA in physics.

Then, as a 22-year-old graduate apprentice at EMI in 1934, he was part of a team of three which built the first production television set.

[1] Orr-Ewing worked with the BBC from 1937 until 1939, when he joined the Royal Air Force Volunteer Reserve and served in the North Africa, Italy and North-West Europe theatres during World War II and was also General Eisenhower's Chief Radar Officer in 1945.

[6] Orr-Ewing was an amateur radio enthusiast, holding the call sign G5OG until his death.

In November 1976 during the opening of Parliament, prior to his announcement of Presidency of the Radio Society of Great Britain, George Wallace, Baron Wallace of Coslany quipped that Orr-Ewing held an amateur licence and that he was colloquially known as "George Five Old Girl", a play on his call sign using non-standard phonetic alphabet.