> It occurred to me what a curiosity it would be to list all the dukes
> and marquesses from fiction, along with he novel and the writer.
Dozens of mystery writers routinely use the Victorian country house as
a backdrop.
Dorothy Sayers wrote of Lord Peter Wimsey, whose father & then brother
were the Dukes of Denver. (Already mentioned.)
Robin Paige's series starring Lord & Lady Sheridan always feature real
historical characters - these have included the Prince of Wales (who
is a duke), the Countess of Warwick, the Duke & Duchess of
Marlborough, and the episode at Glamis Castle maintains that Albert
Victor, the Duke of Clarence & Avondale, was hidden at that castle
until his death during the reign of his younger brother.
Ngaio Marsh's Roderick Alleyn is the heir to his brother's baronetcy -
a lowly title - but higher ups are involved in a number of his cases.
Anne Perry has members of the nobility at several levels appear in her
William Monk series (Do not confuse with TV detective Monk), her
Thomas & Charlotte Pitt series, & her five-part Reavley series.
-- Stephen Stillwell