Thanks very much for responding so quickly. I apologize for having taken so long in replying.
I've searched the Net for this fellow - and have come up against one great brick-wall. There's nothing there about him.
It looks as though I'm going to have to rely on any info my father's 1st cousin, Caroline nee TRIST, might have about him. Caroline is in Wimbledon, UK - intending a visit next May. She has confirmed that Loveday WARREN was RD's wife.
I have a Mary FERRIS and her sister, Susan Jane FERRIS, in my database. SJF married Octavius WILLIAMS at Truro in 1829. I've not located the name of these girl's parents (yet). Mary was born 1821 at Truro & in the 1871 Census, was unmarried & living at her brother-in-law's (OW's)place.