Although I am white, and therefore look identical to a 'Brit', I am of origin and identify myself as Dutch. I live in the North of England, which I'd say is an area with less ethnic-diversity, and therefore perhaps a bit less tolerant to other cultures (due to their lack of exposure and ignorance towards them).
However, I do sometimes notice that as soon as I tell someone that I am not English, their attitudes towards me change, not in a hateful and racist way, but in a way that they regard me as less than I was before I told where I was from.
I'd say that this is especially the case in England (this is guesswork as I have no other experience), but because England is an island, and therefore has no neighbouring countries flowing freely into it, means that there is less exposure towards people from elsewhere in the world. I also think that English people have a feeling that England is 'The Superpower' in the world, as if this were the 17th century. I also see this in the attitude of learning languages; on mainland Europe children grow up learning their own language, English and possibly several other languages, whilst in England, we aren't really taught other languages as everyone expects other people to speak English.
This is only what I experience, and that only happens when I chose to reveal my ethnicity, so I can only imagine what people who look different (and who'm are associated with bad people) have to put up against.