I largely agree Queenie. Although in this particular instance I do think it's a shame, because there's so little "British heritage" around today. Foreign cultures are often colourful, rich and fascinating, with strong links to their past. What have we got? Fish and chips, dis-used collieries, Robin Hood
However much we laugh at morris men (and we do

), they are a vibrant, wacky piece of our history - our version of tribal dances I suppose. I rather think they should be allowed to keep doing it without this sort of objection.
If they painted big white lips on themselves, that might be another matter...
As to those who make this ridiculous "reverse racism" argument - "why can they say n****r if I can't?" - put your Daily Mail down for a second and put your thinking hat on. If there was something different about you - perhaps you're obese, have an obvious birthmark, have alopecia or something, and in the past have been teased and singled out for it, do you think it's OK for people to make jokes about it? No. But if you feel confident enough to make a self-deprecating joke about it to lighten things up and make other people feel less awkward, is that OK? Yes!
Yes, I think the whole "claiming back offensive terms = empowerment" thing is a bit silly, but in terms of black comedians making "racist" jokes, what's the problem? Black people and white people can laugh along together and become closer through it.
The reason you (as a white person) are not allowed to tell those jokes is because of the history of our respective ancestors. If your grandad had murdered someone elses grandad, would you be telling that guy jokes about killing people? No - it's not about you being personally to blame, it's about showing that you acknowledge the errors of the past, and your desire to distance yourself from them. If that other guy then decides to lighten the mood by telling a joke about killing people, that's his decision and it's OK. Easy.