The Foundling (by Georgette Heyer)

I re-read my collection of Georgette Heyer novels regularly, and usually find that even if I recall the overall storyline, there’s a lot which I have forgotten. That’s certainly true of ‘The Foundling’ which I last read in 2018. I remembered that a young, beautiful and not very bright young woman was rescued by an altruistic nobleman, but I had somehow muddled the plot, in my mind, with ‘Charity Girl’. 
There are undoubtedly similarities between the two rescues, and the characters of the heroe...