Why does it look like there are closet racists in the UK?

I heard that many people have voted for the BNP, on this section you get people asking why whites are racist and people say that they are not all racists, and i agree but now i am not so sure. Are the people I once thought of as friends really the enemy. In public people don't admit they are racist but now the BNP has a seat. What is so wrong with multiculturalism. White Brits are a mix of Romans , Saxons, Normans, Vikings, Goths and other groups so in a way they aren't as British as they think.