William Poland was born in Portsmouth, Hampshire, on 18 July 1915, the son of Lieutenant Allan Poland, Royal Navy, and his wife Phyllis (née Weston). At the time of the 1921 Census William Poland was at home with his parents and his sister Pamela at Cliffe Cottage, Blackgang, Isle of Wight and his father was noted as a Lieutenant Commander serving in HMS K22.

William Poland joined the Royal Navy as a Cadet on 1 September 1932 and was appointed to the cruiser HMS YORK. He was promoted to Midshipman on 1 May 1933 and was appointed to the cruiser HMS SUFFOLK on the China Station on 5 August 1933.

He joined submarines on 4 January 1937 with an appointment to HMS DOLPHIN ‘for Submarine Training’. He was appointed to ‘Submarine HMS THETIS as the Navigator – Completing at Cammell Lairds at Birkenhead’ on 17 December 1938. William Poland of Berins Hill, Ipsden, Oxfordshire, who died in the accidental loss of HMS THETIS in Liverpool Bay on 3rd June 1939, was later buried in the THETIS Mass Grave at Holyhead. He was unmarried and his estate was left to his father, Rear Admiral Allan Poland, at Berins Hill, Ipsden, Oxfordshire.