Born at Singapore in 1876 the son of the Rev William Aitken, he was educated at George Watson's College and the University of Edinburgh. After holding resident posts there and in Liverpool he was appointed to the Bolingbroke Hospital, Wandsworth Common. He took the Fellowship in 1908 and specialised in orthopaedics, his chief work being at St Vincent's, Pinner, which he developed from a cripples' home to a large open-air orthopaedic centre. Aitken was closely associated with Sir Robert Jones for nearly thirty years and worked with him at the Military Orthopaedic Hospital, Shepherd's Bush during the first world war. He described this war-time experience in *The Lancet* (1917, 1, 10-16) and in the *Transactions* (1917, 40, 27-37) of the Medical Society of London. Under Jones's influence he developed great skill as a manipulator and became keenly interested in after-care, in the tradition of Jones's uncle and teacher Hugh Owen Thomas, whose life Aitken admirably recorded in his book *Hugh Owen Thomas, his principles and practice* (1935). He was for many years a director of the Robert Jones and Agnes Hunt Hospital at Oswestry and consulting orthopaedic surgeon to Faversham Hospital. He was a founder and afterwards President of the Orthopaedic section of the Royal Society of Medicine. Aitken collaborated with Robert Jones in writing the chapter on "Deformities" in Latham and English's *System of treatment* (1912), he wrote on "Scoliosis" for the *Robert Jones Birthday Volume* (1928), and delivered the H O Thomas memorial lecture at Liverpool in 1931 on "Rest and movement in the treatment of lesions of joints" (*Liverpool med-chir J* 39, part 2, pp 103-126). He was a frail man with a barking voice, and liable to fits of coughing. His recreation was yachting. He practised at 89 Harley Street, and died on 9 July 1954 at his country home The Old Vicarage, Mansergh, Kirkby Lonsdale, Westmorland, aged 77.