He was the son of John Hancock, a gentleman of Guildersfield, Streatham. In 1886 Walter Hancock joined George Frederick and possibly Thomas Parson and as a partner in the business which was re-named Watson & Hancock.
They continued to trade from 308 High Holborn. However, in 1891 the firm became W T Hancock & Co. This must have been when Thomas of Kensington, George F and possibly Charles Henry and Thomas Parson left the business. Arthur Henry became an electrical engineer. Thomas of Kensington, George F joined Watson Brothers. In the 1891 census Thomas of Kensington (described as a gunmaker) and Mary Louisa were recorded living at 21 Haycroft Road, Lambeth, very near to the Hancock family, with their daughters Constance Amelia (b.1884) and Doris Mary (b.1885).
The 1891 census records Arthur Henry Watson living at 36 Griffiths Road, Wimbledon with his wife Mary Ann (b.1861 in Gloucester, Gloucestershire) and their children Hilda E (b.1887), Clarice Laura (b.1889) and Arthur Dudley (b.1890). Incidentally, the 1891 census records Thomas Parson Watson as an optician living at Delves House, Streatham, with his wife and children. William (I)'s widow Elizabeth, aged 68, was recorded living at Grassmere, Ambleside Avenue, Streatham with Elizabeth M, Charles Henry, a cook, domestic servant and housemaid. Charles H was described as an optician.
Walter Hancock was recorded in the 1891 census living at 30 Kensington Park Road with his wife Mary Winifred. He described himself as a gun and fishing tackle maker.
In 1896 W T Hancock & Co were recorded at 308 High Holborn and also at 4 Pall Mall although they probably moved there in September 1894. In 1899 W T Hancock & Co was recorded for the last time at both 4 Pall Mall and 308 High Holborn. Whether the firm closed or was sold to Watson Brothers or someone else is not known. In the 1901 census Walter Hancock was living at 23 Kildare Terrace, Paddington with Mary Winifred. He described himself simply as an employer.
The 1911 census records him as a widower living with his daughter Winifred Marion. He described himself as a sports salesman.