McGofH is probably right in that the absense of the plantation system in Great Britain has to be a significant reason for the UK's lack of a distict, independent (and segregated) black culture like that in the US.

However, I do still think that there have always *much* greater numbers of African-descended people here in the US than in the UK, and that the weight of sheer numbers also makes a qualitative difference between the situations on either side of the ocean.

Also, as a number of British correspondents have pointed out, Black Brits were historically able not only to assimilate into the larger culture, but even to eventually "disappear" into the general population, over generations, due to intermarriage.