Born on December 29th, 1845, at Berbice, New Amsterdam, British Guiana, posthumously, his father, a missionary, having died of yellow fever six months before. Brought to England at the age of six months, he was placed under the care of an uncle, and after leaving school studied medicine at Manchester, Edinburgh, Queen's College Belfast, University College London, Paris, and Vienna, in the course of which he became proficient in French and German. After graduation he served as Ship's Surgeon and had charge of invalids, military and naval, homeward bound from China, East Indies, Mauritius, and the Cape. During the Franco-German War, 1870-1871, he saw service as an Ambulance Surgeon at Metz, Sedan, Coulmier, and Orleans, during which he came under the notice of Sir William MacCormac, Chief of the Anglo-American Ambulance at Metz and Sedan. He accompanied Surgeon General Langenbeck on his tour of inspection of German Military Hospitals. For his services Mackellar was made a Knight of the Military Order of Merit of Bavaria. In February, 1872, he was appointed Assistant Medical Officer to the Royal Free Hospital, and after becoming FRCS in 1873, Resident Assistant Surgeon at St Thomas's Hospital. He held that post until elected Assistant Surgeon to St Thomas's Hospital. During the Turco-Servian War of 1876 he acted as Surgeon-in-Chief of the Stafford House Committee's Ambulance, was present at all the chief actions, and was made a Knight of the Gold Cross of Takovo. During the Russo-Turkish War in 1877 he was Consulting Surgeon to the 5th Ambulance of the Red Crescent, serving in and around Plevna, for which he was made a Knight of the Order of Medjidie. Archibald Forbes, the War Correspondent of the *Daily News*, described how a fragment of shell penetrated the room in which Mackellar was operating, and narrowly missed him. He turned round, merely remarked that it was 'a close shave', and went on steadily with his operation. He became full Surgeon at St Thomas's at the age of 41, and Senior Surgeon at 48; for years he taught practical surgery and operative surgery; he lectured on forensic medicine, and besides was Examiner in Surgery at the University of Glasgow. He was also Surgeon to the French Hospital in Soho. He was appointed in 1885 Surgeon to the Metropolitan Police in succession to Timothy Holmes (qv), and soon became absorbed in the duties of the post. The salary was small, based on a part-time estimate, but the Police Force underwent great increase, and he found himself excluded from private practice. He did much to improve the official recognition of the Divisional Surgeons, and in spreading a knowledge of 'first aid' and of ambulance methods. Largely owing to official parsimony in the later years of his time, there was found much leeway to make up when he was succeeded by his junior colleague, Sir Charles Ballance. In 1903 he gave up his London house, 7A Wimpole Street, and went to live at Pinner. His health had never been completely regained after a severe attack of pneumonia in 1895, and he died after a short, acute attack on June 15th, 1904, He was survived by his widow. Mackellar's most notable contribution was the "Introductory Address" on his various war experiences given at St Thomas's Hospital in 1885. The Library of the College contains the notes of Lister's lectures in the autumn of 1864 taken in shorthand by Mackellar and afterwards transcribed. The volume was presented by Sir D'Arcy Power, KBE, in 1928.