If you're new to Britain, the sheer variety in accents spoken across the country can be surprising. Most non-British people have heard two: the stereotypical aristocratic accent (also called Queen's English or Received Pronunciation); and cockney, the working class accent from London (think Michael Caine). But there are at least a dozen more:
I don't have data to prove it, but I think the diversity of accents in Britain is relatively unusual. Differences in speech across the whole continent of North America seem relatively modest compared to the differences between cockney and geordie.