The BNP are not football related and neither is the black gang culture prominent in the poorer parts of London. These are key fabrics of society who have a voice and they use it to the detriment of this country's principles.
The BNP have 3 seats out of over 20,000 in local government. That's hardly a 'voice'. I will concede though that their influence is very much there, they're never far from the front pages. That said, racism in football is also well documented, as well as black gang crime, as you say.
Eliminating it is a complicated matter though, one that is too complicated for any authorities to devote serious funds to doing so.