Percy was educated at Queen's College, Cork, where he was senior exhibitioner and graduated as B.A.O., M.B. and B.Ch. of the Royal University, Ireland in 1906. After serving as senior house-surgeon of the Prince of Wales General Hospital and Cancer Hospital, and as pathologist to the Royal Hospital for Diseases of the Chest and to the City of London Hospital for Disease of the Chest, he became assistant pathologist and curator of the museum of King's College Hospital and lectuer on morbid anatomy to the hospital medical school. He had only recently joined the 4th London General Hospital as a captain. He died at Denmark Hill, London of pneumonia. He was the son of Edward Robert and Margaret Ridge.