Catharine ('Kate') Louisa Boughton was probably the sister of Henrietta G. Cullen, who was two years older than her, and living in 1881 with Catharine and her husband, the painter George Henry Boughton, at West House, Campden Road, London. They had an adopted daughter called Florence, who Whistler fondly referred to as Flossie, who became Mrs J. Montague Robb.
In the early 1860s Catherine Boughton and her husband settled in London, where they became known for their entertaining Sunday dinners. They were friendly with Whistler who had become George Boughton's friend while he was studying in Paris in 1860. Their friendship continued into the 1880s when they were among those invited to Whistler's famous Sunday breakfasts [#00372]. In 1888 Whistler made Catherine a present of a little etching. She responded by saying that 'nothing has given me so much pleasure as your beautiful works' [#00374].
UK census 1881 from http://www.familysearch.org (accessed 2004.03); Boughton, G. H., 'A Few of the Various Whistlers I have Known', Studio, vol. 30, December 1903, pp. 208-18; Baldry, Alfred Lys, G. H. Boughton, R. A.: His Life and Work, London, 1904; 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.