Banjiman - People 'whitening' up doesn't offend me in the slightest, and to be fair I am unaware of the Border Morris connection. I always believed that at Rochester Sweeps it was in some way a celebration (a silly way of putting it I know) of the Dickensian method of putting children up the chimney to clean it, and coming out with sooty faces. I will go to the site you suggested and mull it all over.
John Barden