I know this is an old book, but it's annoying that publishers don't read for editing because they're cheap bastards. There are so many times where a character has wrongly addressed someone (e.g., Hubbard, after referring to Poirot as 'Mr Poirot' a dozen times, suddenly calls him 'M Poirot' ... which is the shortening for the French) or people who've used Anglicised names (a French conductor whose name is something Michel being called Michael by his French manager).