Inspector-General Belgrave Ninnis was born on the 1st September 1837 the fourth son of the late Mr Paul Ninnis of St.Austell, Cornwall. He joined the Royal Navy in 1861 as an Assistant Surgeon and on the 23rd august was appointed to the sloop HMS Pantaloon on the Cape of Good Hope Station. He served as a Naturalist in the Imperial and Colonial surveying Schooner, Beatrice, in the Northern Territory of South Australia from 1864-66. On the 26th January 1867 he was appointed to the Royal Hospital, Greenwich, and on the 1st June 1869 to HMS Caledonia, on the Mediterranean Station, where he served until the 2nd May 1872 on appointment to HMS Lord Warden, Flagship of the C in C Mediterranean Fleet, as Surgeon.
He was promoted to Staff Surgeon on the 21st December 1874 and accompanied Sir George Nares' Expedition to the Arctic as Staff Surgeon aboard the Discovery. He became Fleet Surgeon on the 3rd November 1876, and on the 13th October 1878 and was appointed to HMS Garnet, serving off the south-east coast of South America. He was awarded the Sir Gibert Blane Gold Medal in 1879, and became Deputy Director-General of Hospitals and Fleets on the 5th May 1883, retiring on the 1st September 1897 with the rank of Inspector-General.
He became Deputy Commissioner of the St.John Ambulance Brigade and was appointed
Chief Commissioner in 1903. On the 5th July 1911 he received the service medal of the Order of St.John from the hands of H.R.H. Duke of Connaught, who was then Grand Prior of the Order of St.John of jerusalem. he became a Knight of Grace of the Order and was awarded a C.V.O. on the 14th June 1912.
In addition he was a Fellow of the Royal Geographical Society and a Fellow of the Royal Society of Arts, and he published "Remarks on the Ethnology, Natural History, and Meteorology of the Northern Territory of South Australia", and "Diseases incidental to Eskimo Dogs of Smith Sound - Diagnosis and Treatment".
He died on the 18th June 1922, aged 84 in Streatham.
His son Belgrave Edward Sutton Ninnis was killed on the Australian Antarctic Expedition of 1912-14 when he fell into a crevasse on a sledge journey across King George V Land, with Mawson and Mertz.
(Knight of Justice. London Gazette 21.1.1916.)