Reginald Tinniswood was born in Plympton, Devon on 16 June 1895, the son of Arthur Tinniswood, a Royal Artillery Bombardier, and his wife Harriet Alice (née Audoire).  Harriet was a native of Alderney, and his parents had met when his father had been stationed at Fort Tourgis, St Ann’s, Alderney.  Arthur Tinniswood died in 1897 and Harriet married John Bromley, also Royal Artillery, in 1898.  Reginald had a younger sister, and three younger half-siblings.  At the time of the 1911 census, John Bromley was employed in  London as a caretaker, and 15-year old Reginald was a Boy Messenger at the War Office.

He joined the Royal Navy in October 1911 at HMS IMPREGNABLE, the Boys’ training ship at Devonport, and subsequently went to HMS GANGES where he was rated Signal Boy in April 1912.  In December 1912 he joined the battleship HMS CONQUEROR and was rated Ordinary Signalman on his 18th birthday.  In April 1914, he transferred branch, becoming a Stoker 2nd Class, but remained in HMS CONQUEROR and was rated Stoker 1st Class in November 1914.

He joined HMS DOLPHIN on 21 December 1915, moved to HMS MAIDSTONE from February to April 1916, then returned to HMS DOLPHIN.  In March 1917 he was sent to HMS FEARLESS for the newly commissioned HMS K2.  HMS FEARLESS was a scout cruiser and employed as the flotilla cruiser for the Twelfth Submarine Flotilla, consisting of the large steam powered K-class submarines intended for operation with the Grand Fleet, based at Scapa Flow.  On 21 September 1917, Reginald Tinniswood was lost overboard from K2 and drowned, but nothing more is known about the circumstances of his death.  His body was not recovered and he is commemorated on the Plymouth Naval Memorial.

He left a widow, Emily Alice Ellen (née Childs) whom he had married earlier in 1917.