oops, wrong button.
This has been argued about here, over the years
and the main difference now seems to be that the person who ventured to Padstow and tried to engage the locals and ask why, is a gentleman with a dark skin. I suspect that the locals don't really know the history behind it but there's a lot of invented 'folklore' and maybe some of them really do believe what they're told. I'm guessing that, after the previous controversy, they're on the defensive when outsiders question them about it and maybe someone deliberately played that 'good darkies' song, which seems to be a Stephen Foster song.
Cats has posted some knowledgeable answers, in threads from 2005 and 2007.
I personally think that blacking up wasn't part of a Padstow tradition until the 20th C when Minstrel shows and music halls were popular. Someone introduced a banjo into the Mayday band (there are some old photos showing this)and then dressed up to match it.
Mike Waterson sang a cleaned up version of the offensive song, about a dog named Bellman - 'he's gone where the good doggies go'.

Robyn