We favour 'British' books for 'British' people. This works well because the American's are charmed by anything quintessentially British. We can export said product - Kerching! They lap it up, a fact that billionaire Rowling will attest to.
But if we go beyond literature we can see where the industry is missing out. I began to create my theory when Hugh Laurie became the world's highest paid television actor for playing the part of Dr Gregory House in "House". Hugh Laurie is British, and it has come to light that the producers hired him on the strength of his audition tape – they'd no idea he was British. When asked about his accent he blamed it on "A misspent youth spent watching way too much TV."
This was a new twist. For years we'd been sending British actors like Hugh Grant over to play British parts but, secretly, behind the scenes the Brits, were taking over Hollywood – not the just the British parts . . . all of them! There's been a huge backlash in the US film industry as Brits and Aussies take all the best parts. Michael Douglas (remind me who he's married to?) and Spike Lee are leading the revolt. The Chicago Tribune carried an article commenting on how British actors were not only better but able to pull off faultless American accents. Yes, they're better actors because they're better trained but the accents? – Any UK resident under the age of 60 has been pretty much weaned on US film and television from birth.
Having established that on screen the British public appreciate stories based in the US containing US characters it is clear that a market exists. However, if a British writer submits a manuscript containing a story set in the US utilising US characters he is advised to solicit a US based agent.
Why? It makes no sense.