Birley was born in New Zealand whilst his British parents were making a world tour. He was educated at Harrow and Cambridge and was drawn to painting while visiting Europe. He enrolled at the Academie Julien in Paris. A trip to Spain followed where Birley fell under the spell of Velazquez. On his return to Britain, he undertook further training at St John's Wood School of Art, London. During World War I Birley served in the Royal Fusiliers, before joining the Intelligence Corps. After the war he became a successful society portrait painter, and was a particular favourite of the Royal Family. He was knighted in 1949.