Of course Mick, when the Black and White Minstrel show was running in England we didn't have the racial prejudice that there is in the USA.
So the Minstrel Show was considered a rich musical culture and there was nothing racially prejudiced about it.

When slavery was abolished in Britain the whole black population was absorbed within three generations.

The cruelty to slaves in the Southern States was some of the worst cruelty ever inflict by humans upon one another.

But I think that the "Black Face" versus the "Black Voice" thing is more a matter of the fact that stimuli received visually have more impact than those received aurally.

That coupled with the fact that many who are overly politically correct respond to immediate reaction and have a tendency not to listen. This has resulted in the loss of a musical tradition, which is a very sad thing.

Let us hope that they keep 'not listening' or we are likely to find that white folks will not be allowed to sing The Blues.