Frederick Jameson was the son of Mary Ann Jameson, née Gurney, and William Kingsbury Jameson, merchant. Frederick married Ellen and they had a daughter, Evelyn M. (b. ca 1880). Ellen was present at Frederick's death, at Saxonbury Lodge, Frant, Ticehurst, in 1916.
JW certainly knew Mrs Jameson, around 1892, and possibly earlier.
UK census 1881, from http://www.familysearch.org (accessed 2004); GPO birth certificate for Frederick Jameson, Sub-district of Wadhurst, County of East Susses, 1916.