regshoe

:D

Keith has given his parole—essentially, he agrees not to try and escape in return for Ewen promising not to physically stop him from escaping—hence why he's just hanging around Ewen's house rather than being locked up somewhere. Yeah, possibly killing him outright in their initial encounter would have been too aggressive, and from Ewen's perspective there's not really any reason to (Keith is injured, he's not a serious threat to Ewen and it would hardly be fair!). Meeting a regiment of Highlanders in battle, where it's kill or be killed, is a different thing (although, in the end, most of the recruits at High Bridge were only taken prisoner—again, I suppose, no reason to kill them).

Parole prisoners turn up a lot in Broster's novels—she loves the situations created by those gentlemanly codes of honour (this option was only available to officers i.e. gentlemen). There was a bit of a debacle later on in the '45 where a group of Hanoverian officers on parole were forced by their own commanders to break their paroles, escape and return to fighting—which some of them resisted, seeing it as against their code of honour.