”Mr Rowl” by D. K. Broster (1877 – 1950)

Raoul des Sablières, a French parole prisoner in England during the Napoleonic Wars, becomes enmeshed in a complicated tangle where his honour conflicts with his parole, and is sent to prison. Juliana Forrest, for whose sake he broke his parole, does her utmost to save him, and in his adventures and misfortunes, Raoul eventually also finds help from an unlikely source. This is a fun adventure story and romance, written in a style similar to Georgette Heyer.