Here's a brief history of black performers in Britain from the V&A Museum website, with some links to more detailed information: Timeline: Black Performance in Britain.

The timeline for the 18th century uses a picture by the artist William Hogarth; in fact the works of Hogarth contain a large number of images of black people in London of that time, but what is strange is that nobody seemed to notice this until David Dabydeen drew attention to it in his 1987 book Hogarth's Blacks.

David Dabydeen is also one of the editors of the recent Oxford Companion to Black British History which is a very useful guide indeed.

Matthew Edwards