Lord Walter Campbell was the third son of Lord George Douglas Campbell, the eighth Duke of Argyll, and Lady Elizabeth Georgiana Campbell, née Sutherland-Leveson-Gower. In 1874 he married Olivia Rowlandson, daughter of John Clarkson Milns of Radcliffe Bridge, Lancashire. They had two children, Douglas Walter (b. 1877) and Lilah Olive (b. 1875). Lady Olivia Campbell remarried in 1890, following the death of Lord Walter Campbell in 1889. She married Allan Gordon of 38 James Street, Buckingham Gate, London.
Lord Walter Campbell was one of twelve children. His brothers were John George Edward Henry Douglas Sutherland, the Marquess of Lorne (b. 1845); Archibald, a soldier, writer and businessman (b. 1846); George Granville, a lieutenant in the Royal Navy (b. 1850); and Colin Campell, M.P. for Argyllshire from 1878 to 1885 (b. 1853). His sisters were Edith, Countess Percy (b. 1849); Elizabeth (b. 1852); Victoria (b. 1854); Evelyn (b. 1855); Frances (b. 1858); Mary Emma (b. 1859); and Constance Harriet (b. 1864).
Lord Walter Campbell's brother and sister-in-law Lord and Lady Archibald Campbell were important patrons of Whistler who helped to restore his artistic position in London following his bankruptcy in 1879 (see Portrait of Lady Archibald Campbell in Court Dress (YMSM 240), The Grey Lady: Portrait of Lady Archibald Campbell (YMSM 241), Arrangement in Black: La Dame au brodequin jaune - Portrait of Lady Archibald Campbell (YMSM 242), Note in Green and Brown: Orlando at Coombe (YMSM 317) and r. and v.: Trellis (M.848)). They had two children. Their son Niall Diarmid succeeded his uncle as the tenth Duke of Argyll.
Lord and Lady Colin Campbell also commissioned a painting from Whistler, Harmony in White and Ivory: Portrait of Lady Colin Campbell (YMSM 354), a painting which was executed during Lady Gertrude Elizabeth Campbell's divorce hearing.
Debrett's Peerage, Baronetage and Knightage, London, 1896; Young, Andrew McLaren, Margaret F. MacDonald, Robin Spencer and Hamish Miles, The Paintings of James McNeill Whistler, New Haven and London, 1980; MacDonald, Margaret F., James McNeill Whistler. Drawings, Pastels and Watercolours. A Catalogue Raisonné, New Haven and London, 1995.