Born in Snaresbrook, Essex, Mary attended the Central High School in Newcastle. After Oxford, she joined the Board of Education as a junior civil servant. From 1939 she was founding secretary of CEMA (Committee for the Encouragement of the Arts in Great Britain) and when it was reorganised in 1945 as the Arts Council of Great Britain, under the chairmanship of John Maynard Keynes, she became the first secretary-general, a post she held until 1951. She and Ifor Evans were largely responsible for implementing Keynes' ideals in post-war Britain.
She then turned her talents to work as a translator, literary agent, writer and film censor. In 1956 she founded the famous Mary Glasgow Publications to introduce enjoyment into Modern language teaching was honoured by both the French and British governments (CBE). She became chairman of the Modern Language Association and President of the Institute of Linguists, as well as founding the Mary Glasgow Language Trust. Mary learned to fly when she was 70 and flew herself to and from her chateau in Provence.