I draw your attention to the Waltham 'Black Act' 1723
This Act of Parliament which proscribed the disguising by blacking the face, on pain of death. The 'Waltham Black Act', was fully entitled;

'An Act for the more effectual punishing wicked and evil disposed Persons going armed in Disguise, and doing Injuries and Violences to the Persons and Properties of His Majesty's Subjects, and for the more speedy bringing the Offenders to Justice.'

This act was so punitive that one writer suggests that a study of this one statute is fundamental to the understanding of the use of the Death penalty in the 18th century. Its intention was to proscribe any and all activities where people committed criminal acts whilst disguised especially by the blacking of the face. Hence the name of the act. The 'Black Act' was repealed only in 1827, one supposes that this date might occasion a national celebration and, perhaps, a sudden upsurge in 'face-backing' in recognition of the removal of a draconin legislation? A short extract of the Act is shown here;

'For the preventing which wicked and unlawful practices, be it enacted by the King's most excellent Majesty, by and with the advice and consent of the lords spiritual and temporal and commons, in parliament assembled, and by the authority of the same. That if any
person or persons, from and after the first day of June in the year of our Lord one thousand seven hundred and twenty-three, being armed with swords, fire-arms, or other offensive weapons, and having his or their faces blacked, or being otherwise disguised, shall appear in any forest, chase, park, paddock, or grounds inclosed with any wall, pale, or other fence, wherein any deer have been or shall be usually kept, or in any warren or place where hares or conies have been or shall be usually kept, or in any high road, open heath, common or down, or shall unlawfully and wilfully hunt, wound, kill, destroy, or steal any red or fallow deer,'

So it can seen that the tradition of black-face as disguise was well known and actually has been enshrined in British Law.

Now if you start to peruse the newspaper reports of the last two hundred years for incidence of black faced morris dancers you might be surprised to note that they occur, almost invariably after 1830 - wonder why?

Incidentally, the Royal Marines, SAS etc use black face make-up for disguise in night ops. Why aren't the 'right on' PCers calling this practice racist? I suspect its because Morris Dancers are seen as a softer target that the Armed Forces! Enjoy.