Nigel,
I can't thank you enough for all the information you've provided about William Kneale and his family. You state that he remarried. Do you happen to know when his first wife, Elizabeth Gell, died? You also mention that Elizabeth Gell's first cousin was your great-grandmother. Was your great-grandmother a daughter of Margaret Ann Faragher (1826-1897) and Richard Clucas Quine (b. 1822)?
Bill Burton