Source: Michael Doyle Their Name Liveth For Evermore: The Great War Roll of Honour for Leicestershire and Rutland.
He was the son of Thomas Castle a hosiery trade trimmer, born 1846 in Hinckley, Leics., and his wife Rhoda Castle (nee Hill), a housekeeper, born 1842 in Smeeton Westerby, Leics. John was born in 1883 in Hinckley, Leics., his siblings were, Thomas, born 1868, Frederick, born 1869, James, born 1874, Lizzie, born 1878 and Alfred, born 1882, all his siblings were born in Hinckley, Leics., in April 1891 the family home was at 7 & 8, Baileys Yard, Castle Street, Hinckley, Leics. In March 1901 John was employed as a light porter and was residing at 55, Bardolph Street, Leicester, this being the home of his brother in law, Francis Smith a gas stoker, born 1857 in Hinckley, Leics., and his wife, Sarah A. Smith (nee Hill), born 1861 in Dunton Bassett, Leics., and their children, Elizabeth, born 1881, Francis, born 1883 and Harriett, born 1891. In April 1911 John was employed as a coal miner fitter and was residing in the family home at Wyatts Yard, Bedworth, Warwks., together with his wife of five years, Jane, born 1886 in Collycroft, Warwks., and their children, Elsie, born 1907 in Hinckley, Leics., and Patience, born 1909 in Collycroft, Warwks., also residing in the family home was his brother in law, John Handley a coal miner, born 1879 in Collycroft, Warwks. His father was born with the surname spelling of Castle, and married with that spelling, however the surname appears then to change to the spelling Cassell, which is used in later records and John was registered at birth as Cassell.