He was educated at Charterhouse School before studying at Pembroke College, Cambridge from 1924 to 1927, and completed his medical training in 1930 at St Thomas' Hospital. Subsequently, he worked as a surgeon at both St Thomas' and Moorfields Eye Hospital in London, specialising in ophthalmology. In 1938 Ridley was appointed full surgeon and consultant at Moorfields Hospital and later appointed consultant surgeon in 1946.