For every black person who is not offended, there is one that is and probably twice that number of white people taking offence on behalf of black people.

I don't think blackface Border has anything to do with Minstrelsy, which a few here seem to hang everything on, nor do I think those that apply Blackface are inherently or actually racist. Nor do I think that the huge number of Border sides have any clue as to the history of Blackface beyond the advent of the Shropshire Bedlams in 1975 - a side that has moved on from Blackface.

However, if you perform in multi-cultural Britain blacked-up you need to be aware of cultural sensibilities and sensitivities. You might not care about that but others might not care about your "tradition".