Whatever happened to Cadman?

I'm reading Trouble for Lucia for the first time, and being assured of Foljambe's continued employment in the Pillson-Lucas household, I'm rather surpassed to find that Lucia had engaged a new chauffeur, Chapman. Whatever had become of the loyal Cadman?

If there are revelations within the book, please answer with spoiler tags, and I'll check out such comments when I've concluded, otherwise, information and/or speculation awaited with bated breath.

That's just another example of Fred's not paying attention.

>2 nbtOO: I eventually gathered that, although I think there's material for a crossover "Poirot and Lucia" detective story in which they both vie to become Tilling's premier sleuth by solving the mystery of the Vanishing Chauffeur.