Undoubtedly many of our traditions we like to think of as going back many centuries in fact are linked to minstrelsy. Some of the tunes used are indeed minstrel tunes and in my own part of the world in the early years of the last century the N word was used freely, but not in a derogatory way. Bacup has been mentioned.

To add a little to the historical context not fully explained by Hutton, minstrel-type blacking up by performers goes back to the late 18th century (solo artistes only). The main thrust in Britain came in about 1840 when following their enormous success in America the first troupes came over here and were equally an enormous success. (Think The Beatles) Their tunes and performances were understandably immediately incorporated into our existing traditions.

This is not to say blacking up did not predate this. The principal effect was disguise and the quickest/cheapest way to effect this was soot or burnt cork or similar.