William Hilmer was a partner in a nationwide photography firm in the late nineteenth and early twentieth centuries. In 1894 he married fellow photographer Elizabeth Zilpha Mentor in Southampton. Trading as E Mentor and Co, the couple ran photography studios in towns all over the country including Southampton, Brighton, Portsmouth, Cheltenham, Bournemouth, Southsea, Wolverhampton, Coventry, Birmingham, Kidderminster and Barrow in Furness.
In the 1870s Hilmer worked as a drapers assistant in Cheltenham. He married in 1875, but when he moved to Portswood, Southampton with his widowed mother in the late 1880s his wife was not with them. The 1891 census recorded Hilmer as a photographer.
In early 1894 Hilmer's first wife died, and later that year he married Elizabeth Zilpha Mentor. In 1896 he opened a studio in Bournemeouth trading as Hilmer and Co. However, after this time all the studios were in the name of E. Mentor and Co.
Even though the firm traded as E Mentor and Co, the 1901 census did not record an occupation for Elizabeth. Hilmer was listed as a photographer and employer.
In 1911 Hilmer and his wife and daughter lived in Piecombe, Sussex. Both of them were living on their own means and no longer working. In later years they retired to the Isle of Wight, were Hilmer died in Ventnor in 1943.