Mary (Eustacia) Dalrymple Smith was the wife of Eustace Smith (1831-1903), a ship owner and ship builder. They had ten children (six daughters and four sons). The eldest daughter was Maye (1856-1914), the wife of Ashton Wentworth Dilke, MP, and maternal grandmother of the Roskill brothers.
She may have known JW in the mid-seventies, when her name appears in an address book (#12714).
MacLeod, Dianne Sachko, Art and the Victorian Middle Class: Money and the Making of Cultural Identity, Cambridge, 1996; 'The Dilke-Crawford-Roskill Papers', at http://janus.lib.cam.ac.uk (accessed 2005).