Born in 1856 the son of Captain Charles Edward Mortimer, 4th Middlesex Militia, and his wife Mary Jane Fanstone. He was educated at Bristol and at the Westminster Hospital and St Bartholomew's. He served for a period as prosector at the Royal College of Surgeons. He first intended to practise as an alienist, and held the appointments of resident house physician and resident clinical assistant at the Royal Bethlehem Hospital and assistant medical officer at Portsmouth Borough Asylum. He won the certificate of the Medico-Psychological Association in 1887 and was awarded the Gaskell prize and gold medal. He published papers on general paralysis of the insane in *The Lancet*, 1889, the year in which he took the Fellowship, and in the *Journal of Mental Science*, 1895. He served as resident obstetrician at the Westminster Hospital and surgical registrar at the Hospital for Sick Children, Great Ormond Street, and was clinical assistant at the Royal Westminster Ophthalmic Hospital. He then decided to specialize as an anaesthetist and was appointed in that capacity to the staff of the West End Hospital for Diseases of the Nervous System and the Royal Waterloo Hospital for Children and Women. He was ultimately consulting anaesthetist to St Peter's Hospital for Stone, to the Central London and the Golden Square Throat Hospital and to the Royal National Orthopaedic Hospital. Mortimer lived at different times at 23 Cheyne Walk, Chelsea, with consulting rooms 23 Fenchurch Street in the City, at 20 Balcombe Street, SW, and 15 St Leonard's Terrace, Chelsea. He was a member of the West London Medico-Chirurgical Society and a vice-president of the Chelsea Clinical Society. Mortimer married in 1882 Katharine Crowe, who died before him. After retirement he lived at the Gray Bungalow, Stodmarsh Road Canterbury, where he died on 16 March 1942, aged 86, survived by his two daughters. Publications: Is general paralysis of the insane necessarily an anomalous and hopeless disease? *Lancet*, 1889, 1, 524. On the treatment of intussusception by injection or inflation, and its dangers. *Lancet*, 1891, 1, 1144. On the non-specific nature of general paralysis of the insane. *J ment Sci* 1895, 41, 759. *Home nursing of sick children* London, 1900 82 pp. Remarks on 1,000 anaesthetizations. *West Lond med J* 1902, 7, 178. The anaesthetization of children. *Med Mag* 1905, 14, 113. On post-anaesthetic vomiting. Lancet, 1911, 1, 1634. Anaesthetics in intestinal obstruction; the value of gastric lavage. *Ibid* 2, 123. *Anaesthesia and analgesia*. London, 1911 276 pp. On the need for choosing the anaesthetic. *West Lond med J* 1911, 16, 28.