George Grinham was born on 12 September 1886 at Croydon, the seventh of eleven surviving children of Douglas Standen Grinham, a painter and decorator, and his wife Mary Ann (née Harvey).

He joined the Royal Navy in February 1902 at the Boys’ Training Ship HMS LION and, after several brief training and harbour roles, joined the cruiser HMS BARHAM in October 1905. He was rated Able Seaman in July 1906. He subsequently served in the cruiser HMS CRESSY, following which he trained as a Torpedoman. He then served in destroyers, based on the depot ships HMS BLENHEIM and HMS TYNE, before being drafted to the scout cruiser HMS SENTINEL which undertook a range of East Coast defence duties during 1914 and 1915.

On 1 January 1916 he joined HMS DOLPHIN, home of the Second Submarine Flotilla providing submarine training and local defence for Portsmouth. It is not clear which, if any, other submarines he may have served in from this date but he was accidentally lost overboard and drowned from HMS B1 on 16 June 1916.  

He left a widow, Elsie Gertrude (née Randle) whom he had married in 1908, and a son, Peter George, born in 1909.   He is buried at Haslar Royal Naval Cemetery.