Hey, lots of guys and one gal later appeared on Hornblower.
Josefina, a Spanish aristocrat, is Senora Ortega (Katia Caballero).
Major Nairn is dying Captain Keene (Michael Byrne).
Colonel Fletcher is Lieutenant Buckland (Nicholas Jones)
Matt Truman is Gunner Hobbs (Philip Glenister).
Mr Tapling of the diplomatic service is Runciman (Ian McNeice).
Napoleon, Boney himself, is Steward James Doughty (Ron Cook). Holly crap, no wonder sailor Styles hated him so much.
What Could Have Been: PaulMcGann was originally cast as Richard Sharpe, but he broke his leg while playing football only a few days into the shooting of Sharpe's Rifles. Sean Bean was recast in the role and... well, you know the rest.
Writing by the Seat of Your Pants: Cornwell does plan his novels in advance, but has admitted to changing them up midway through because he thinks it reads better. An example - Frederickson was supposed to marry Lucille in Sharpe's Revenge.