Who would have won had Anatoly Karpov played Bobby Fischer?

[Brendan Brown]

There are a couple of books I have that discuss the negotiations for the match that never was between Morphy and Staunton:-

Psychology of a Chess Player (Reuben Fine)
The Genius of Paul Morphy (Chris Ward)

Fine says Morphy made repeated declarations that he was not a professional.
In Ward's book, it mentions Staunton dismissed the challenge by saying that "the best players in Europe are not chess professionals and have other more serious avocations".

I must hunt out the David Lawson book on Morphy.

Happy to stand corrected on the Morphy marriage rebuff story. If Hollywood ever makes a film about Morphy I'm sure they'd put that in.