Ernest was born on 31st November 1874 in Tiverton, Devon, the son of James Pook and Ellen (nee Maeers). His father originated from Skilgate, Somerset and variously worked as a thatcher and a railway labourer. Ernest was the eldest of 11 children and by the time of the 1891 census he aged 16 and was working as a general labourer whilst still living at home.
On 19th September 1893 he enlisted in the Royal Marine Light Infantry in Plymouth. In May 1900, whilst on leave in Tiverton, he married Mary Newbury. By the time of the 1901 census, he had been promoted to Corporal second class and was serving on the Leander class cruiser HMS Amphion. The 1911 census found him in Gibraltar as a Master at Arms on board the battleship HMS Queen. Meanwhile his wife had remained in Tiverton looking after their three children, Ellen born in 1905, James born in 1908 and Francis born in 1911.
In 1916 Ernest was serving as Master at Arms on board the battlecruiser HMS Indefatigable. This ship was part of the Second Battlecruiser Squadron and during the Battle of Jutland it was hit by German shells and its magazine exploded. It sank on 31st May 1916 and virtually all the crew, includiong Ernest, were lost. He is commemorated on the Plymouth War Memorial. His younger brother George also fought in the War, taking part in the Zeebrugge Raid in 1918, which he survived.