I followed the Darkie Day thread, but I'm not sure that has anything to do with morris. It seems to me to be a quite different tradition and the only connection so far as I can see is the blacking up. However I don't really know anything about it so I'm reluctant to comment.

As Les says, white people blacking up and mocking black people has a very long and deep history. However here we are talking about white people blacking up for a purpose and in a fashion which has nothing to do with mocking black people.

I would be entirely happy about introducing black British people to our blacking up morris traditions, provided I am allowed to explain that it is not about "mocking black people" but has a quite different origin and function. However I would like to be more certain in my own mind that this assumption is correct.

On the one hand there seems to be little evidence of blacking up before the minstrel craze (but also little evidence the other way, if I understand correctly), on the other hand if it did come from the minstrels I would have expected the morris to have adopted many more aspects of the minstrel identity. This suggests to me that it blacking up had deeper roots - but that's just supposition on my part.