Born at Hoddesdon, Herts, the third son of George Cathrow, who came of an old Scots family. He was apprenticed to Sir John William Fisher (qv), Chief Surgeon to the Metropolitan Police. He then entered St George's Hospital and concluded his professional education at the Hotel-Dieu, Paris. During the first cholera epidemic of 1832 he held the appointment of House Surgeon to the Marylebone Infirmary, and in 1834 settled in practice at 42 Weymouth Street, Portland Place, where he lived for upwards of thirty years. Among his other appointments he was Visiting Apothecary to the Middlesex Hospital and Medical Attendant to the French Protestant School in Bloomsbury. He was also active in the administration of the Society for the Relief of Widows and Orphans of Medical Men. After ceasing to practise in 1868 he resided at Stoke in Buckinghamshire among a little colony of retired medical men, after whom a neighbouring tract of sandy unenclosed land was called 'Doctors' Commons'. Cathrow's life was uneventful. He died of apoplexy on December 15th, 1869, and was buried in the Stoke Poges churchyard.