Born in Southwark on 6 October 1793, he was eldest son of Thomas Key, a medical practitioner, and Margaret Barry. Thomas Hewitt Key was a half-brother by a second marriage. He was educated at Buntingford grammar school, in Hertfordshire, and was apprenticed to his father in 1810.
In 1815 his apprenticeship to his father was cancelled, and he became pupil of Astley Cooper, at a large cost, and in 1817-1818 he lived with Cooper.
Key attended the lectures at the United Borough Hospitals in 1812, and became a pupil at Guy"s Hospital in 1814.
Key became demonstrator of anatomy at Saint Thomas"s Hospital, but resigned the post in February 1823, though he gave some of Cooper"s surgical lectures for two sessions afterwards. he had qualified at the Royal College of Surgeons in 1821, and in the autumn of the same year was appointed the first assistant surgeon to Guy"s, succeeding to a full surgeoncy in January 1824. In this year he introduced the operation for lithotomy with the straight staff, using only a single knife. The success of his operations established his reputation as a surgeon.
He gained a large practice.
In 1825, on the separation of Guy"s from Saint Thomas"s medical schools, Key was appointed lecturer on surgery at Guy"son He resigned the lectureship in 1844.
In 1847 Key was appointed surgeon to Albert, Prince Consort. He died of cholera on 23 August 1849.
At his death he left nine children, including Astley Cooper Key.
In 1845 he was one of the first elected fellows of the Royal College of Surgeons, and in the same year became a member of its council.
