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Governor
Nudity of the condemned seems to have been applied during Middle Ages and the subsequent Modern Epoch, at least before the age of Enlightment. It was particularly applied during execution for 'lower' crimes, including witchcraft and heresy, treason, etc.. Not for a nobleman to be beheaded.
It was likely to humiliate the condemned and make him/her clear that his/her social rights were forfeited. Of course, one could meanwhile cash the sale of their clothes, as a sideward profit.
In the Middle Ages traitors of high social rank, convicted of treason, like Sir Anthony Babington, were stripped stark naked and tied down, spread eagle and face up, to a hurdle, and dragged behind a horse through the streets of London to the place of execution where they would be hanged, drawn and quartered. Thousands of people would line the streets to watch.
During the Renaissance victims of the Borgias were routinely paraded stark naked and on foot or conveyed in carts to the place of their executions and displayed for the crowd. These included priests and nobles and other enemies or perceived enemies.
The humiliation of complete nudity was an essential component of these ultimate punishments.