Ralph Thomas, the son of Serjeant Ralph Thomas, was a law partner of JW's solicitor J. A. Rose. His brother Percy was a painter and etcher. His other brother Edmund was a dealer and print publisher at 39 Old Bond Street in London.
In 1861 JW, who had known the Thomas family since 1860, drew Ralph Thomas (Sr) and Ralph Thomas (Jr) together in the etching The Little Pool (K.74). In 1873 Ralph Thomas (Jr) bought The Forge (K.68) for £3.10.0 (#10628). The following year he published the first catalogue of JW's etchings in London through John Russell Smith and in New York through the dealer and collector Samuel Putnam Avery. The frontispiece, Arrangement in Grey: Portrait of the Painter (YMSM 122), was etched by his brother Percy. The edition was small, consisting of only 50 copies, only 25 of which were available for sale. He had received some of his information from JW's brother-in-law, Francis Seymour Haden, on the condition that his name was not mentioned in the catalogue. Ralph agreed but had to cancel five pages of the print run.
In 1874 JW asked Ralph Thomas (Jr) to supply him with two small plates for his new etching, possibly Reading a book (K.111), Tatting (K.112) or The Muff (K.113), prepared by Percy or the printer Auguste Delâtre (#10892): Ralph Thomas (Jr) believed that nobody printed JW's etchings with the same success as Delâtre.
In 1887 Edmund held an exhibition of The Works of James Whistler, Etchings and Drypoints in his Bond Street gallery (#00172).
Thomas, Ralph, A Catalogue of the Etchings and Dry-points of James Abbott MacNeil [sic] Whistler, London and New York, 1874; Young, Andrew McLaren, Margaret F. MacDonald, Robin Spencer and Hamish Miles, The Paintings of James McNeill Whistler, New Haven and London, 1980.