My favourite set of replies was when the Diane Abbott 'Travellers, Irish people and Jews don't experience racism' story was happening, I would get loads of well-meaning emails from our US readers which would go 'but Stephen, I don't think you understand: there ARE only two races'.

... are they aware who you are

I once got asked (over the phone) if I would mind conducting a "mixed race marriage", once I'd picked my jaw off the floor, I stuttered "erm, which race?" They replied "I don't understand, you know, black and white". They were a lovely couple and we had long talks about it before I married them.

Just like there are two kinds of American - ones that are aware they are parochial and ones that aren't.