As a mummer who "blacks up" quite often, I've never thought that it was a particularly effective disguise. Till last month.

On St Nicholas' night (Dec 6th) I was playing two roles as we were a mummer short. Along with us were a couple: he had joined our morris side a couple of weeks earlier with no previous experience. At the last pub of the evening's tour he was persuaded to take the smaller of my roles, and went off to the gents to put on his face and costume. He returned to the bar before the performance started, and his own wife did not know who it was! (But I did)