Source: Michael Doyle Their Name Liveth For Evermore: The Great War Roll of Honour for Leicestershire and Rutland.
He was the son of Albert Henry Cornelius, an iron turner, born 1874 in Bedminster, Somerset, and his wife Emily Maud Cornelius (nee Donegan, married q3 in the Lambeth, London district), born 1878 in South Lambeth, Surrey. Leonard James was born on the 25th September 1897 in Bedford, his siblings were, Ivy Maud, born 1896, Reginald Albert, born 1899 and Arthur, born 1901, all his siblings were born in Bedford., in March 1901 the family home was at 8, Holme Street, Bedford. In April 1911 Leonard was a schoolboy and was residing in the family home at 90, Grove Road, Leicester, together with his father, now an assurance agent, his mother and siblings, Ivy, a shoe trade trimmer, Reginald, a schoolboy, Kathleen Nora, a schoolgirl, born 1902, Thomas, a schoolboy, born 1904 and Albert Henry, born 1906, the latter three siblings were all born in Bedford. Leonard enlisted into the Royal Navy to serve a 12 year engagement on the 13th March 1914, his reckonable service to commence on the 25th September 1915, he was allocated the service number J/30169 in Plymouth, Devon. His medical examination recorded that he was 5 foot 2¼ inches in height, and he had a chest measurement of 33½ inches, his hair colour was brown and he had brown eyes, his complexion was described as fresh, it was noted that he had a mole on the back of his neck and on his right forearm, and a birth mark in the centre of his back, he gave his trade or calling as seaman. At the age of 18 he was re-examined and his height was recorded as 5 foot 6½ inches and his chest measurement was 36 inches. His record of service began when he joined HMS Impregnable as a Boy 2nd Class on the 13/3/14 – 29/8/14, when he was promoted to Boy 1st Class. HMS Impregnable, 30/8/14 – 17/10/14. HMS Defiance, 18/10/14 – 8/1/15. HMS Defence, 9/1/15 – 24/9/15, when he was promoted to Ordinary Seaman. HMS Defence, 25/9/15 – 31/5/16, when he was killed in action, the circumstance of the action are as follows, HMS Defence was sunk on 31st May 1916 during the Battle of Jutland. HMS Defence was escorting the main body of the Grand Fleet, when the ship was fired upon by one German battle cruiser and four dreadnoughts, as she attempted to engage a disabled German light cruiser. She was struck by two salvoes from the German ships that detonated her rear magazine. The fire from that explosion spread to the ship's secondary magazines, which exploded in turn. There were no survivors.