William Loch married Caroline Eleanor Mary Knightley Burne.
William Loch, CBE, served in the Bengal Infantry, 1862 and on the North West Frontier campaign 1863-64; he was ADC to six Viceroys of India between 1876-1880 and 1884-1903. He was promoted Lieutenant Colonel in 1888. He was Principal of Mayo Chiefs' College, Aymer 1878-1903.
He was in touch with the Whistlers in 1890 when he tried to obtain a copy of the play the Faithful Shepherdess, which had been produced by E. W. Godwin in the early 1880s. Loch may have wanted it for an amateur theatrical performance in India.
Boase, Frederic, Modern English biography: containing many thousand concise memoirs of persons who have died during the years 1851-1900 ... Truro, 1892-1921.