The nephew of John Gunning, Master of the Surgeons' Company (1789-1790). He began a distinguished career as a military surgeon by being appointed Surgeon's Mate on the Hospital Staff, not attached to a regiment, and on Nov 20th, 1793, was commissioned Staff-Surgeon under the command of the Earl of Moira. He received permanent rank as Staff-Surgeon on Sept 12th, 1799, and on Aug 13th, 1805, was superseded, having asked leave to resign on being ordered on foreign service. He was reinstated on June 9th, 1808, and on Sept 17th, 1812, rose to the rank of Deputy Inspector of Hospitals. In February, 1816, he was promoted Inspector of Hospitals (Continent of Europe only), and was placed on half pay on Oct 1st, 1816. His war service included the campaigns of Holland and Flanders (1793-1795), the Peninsular War, and Waterloo. Towards the close of the day at the Battle of Waterloo, Lord Raglan, Military Secretary to Wellington, was standing by the Duke's side, when he was wounded in the right elbow by a bullet from the roof of La Haye Sainte. The arm had to be amputated, and Gunning performed the operation. Raglan bore it without a word, and when it was ended called to the orderly: "Hallo! don't carry away that arm till I have taken off my ring" - a ring which his wife had given him. Gunning went to Paris with Wellington's army, and practised there after the conclusion of peace to the end of his life. He was nominally Surgeon to St George's Hospital from 1800-1823. On New Year's Day, 1863, he was having a dinner party. An attack of bronchitis prevented his receiving his friends on the day expected. His medical attendant thought it serious; but he got better, and on the Saturday was thought to be out of danger. On Sunday morning, Jan 11th, 1863, however, he expired in his arm-chair, without pain, and with scarcely any previous symptoms to denote his approaching end. His daughter, Mrs Bagshawe, the wife of the Queen's Counsel, and two of his grand-daughters were with him at the time of his death. He was then 90 years old, and was the senior member of the Royal College of Surgeons. He is noted by Lieut-Colonel Crawford as being one of the seven officers of the Army Medical Department on whom the CB (Mil) was conferred when medical officers were first made eligible for that honour in 1850.