I treated myself to a copy of Titles and Forms of Address A Guide to Correct Use from the publishers of Who's Who, A & C Black, London. "A reference book for the desk that shows how to address (in speech and on letters and envelopes) men and women with ranks, honours ...etc.,".
I am pleased to have corrected a mistake I made in Monday's Child, the sequel to Sunday's Child. A character introduced another character as Colonel, Viscount Langley, instead of as Colonel, Lord Langley. I have corrected my mistake in the novel. Phew! I do like to be accurate.