Walter was the son of John and Sarah Ann Cooper (née Fairweather).
His father John was born in Norton, Leicestershire, in about 1850 (bap. Norton Juxta Twycross, June 1850), the son of George and Ann Cooper. In 1871 the family was living in Norton. His mother Sarah Ann was born in Measham, Leicestershire, possibly in about 1863, the daughter of Ann Fairweather. Her ages on the census between 1881 and 1911 vary.
According to the information provided by John on the 1911 Census, he and Sarah had been married for 30 years ie 1881, but the only registration of marriage traced is that of John Cooper to Sarah Ann Fairweather in 1884 (reg. A/M/J Market Bosworth). They had 13 children of whom 12 survived infancy: John William b. Hucknall Torkard Nottinghamshire 1880, Harry b. Norton abt. 1882, Mary Jane b. Norton 1884, Walter b. Norton 1886, Joseph b. Norton 1889, Minnie b. Huthwaite (poss. Hucknall under Huthwaite) 1891, George b. Bolsover 1893, Beatrice Mary b. Bolsover 1896, Julia Ann b. Bolsover 1899, Herbert b. Mansfield Woodhouse abt. 1892, Ernest Edward b. Mansfield Woodhouse 1904 and Alfred Sam b. Mansfield Woodhouse 1909.
In 1881 John, a coal miner, Sarah and their son John William were living in Hucknall with Julia Miller, John senior's sister, her husband and children.
John and Sarah probably returned to Norton shortly after the census as their next four children were born there between about 1882 and 1889, but the family was recorded on the 1891 Census living on Newcastle Street, Hucknall: John, a coal miner, Sarah and their children John (10), Harry (8), Mary (6), Walter (4) and Joseph (2). Minnie was born in Hucknall later that year.
The next three children were born in Bolsover between 1893 and about 1899, although by 1901 John and Sarah had moved to 4 Kilburn Terrace, Pleasley Vale Road, Mansfield Woodhouse, where they were living with nine of their 12 chldren: John and Harry who were both coal miners, Mary and Walter who were both cotton mill hands, Joseph, Minnie (9), George (7), Beatrice (4) and Julia (2).
The famlly was recorded at 9 Kilburn Terrace by 1911. John was now employed as a farm labourer. Only nine of their 12 children were still living at home: Harry and Joseph who were both collier/hewers, Minnie a factory hand, George a collier/pony driver (below ground), Beatrice an apprentice dressmaker, Julia, Herbert (9), Ernest (6) and Alfred (2).
Of their other three children, John William, his wife Mary (née Copley m. 1909) and their daughter were living in Albert Square, Mansfield Woodhouse, and while Mary and Walter have not yet been traced on the Census, Mary was probably married while Walter may have already been serving in the army.
The later CWGC record gave Walter's parents' address as 9 Kilburn Terrace. His father may had died in 1935 (reg. Mansfield).
Walter's brother George was also killed in the war while serving with the Machine Gun Corps (see 'Extra information'). According to a report of George's death in a local paper, two other brothers also served, John in the Sherwood Foresters and Joseph in the Royal Engineers. An army disability pension record has been traced for a John William Cooper (23058 Private Notts & Derby Regiment) who was discharged on 9 August 1919.