I really do not think there is as much racial tension or divide in London. However, never have travelled to the USA, perhaps i am not the best qualified to comment.
Certainly, it appears from sites like this that all Black Men are fucking white married women in the USA.
Now we live in Spain, we dont have the kind of ethic mix of the larger cities. We do have a lot of south american people here but, although i have nothing against them, they are not what we are looking for. london did offer that