what was the origin and purpose of funeral mutes?

Perhaps you've read "Oliver Twist" by Charles Dickens? The eponymous hero was sold as an apprentice to an undertaker, who thought that: "There's an expression of melancholy in his face, my dear ... which is very interesting. He would make a delightful mute...". The main purpose of a funeral mute was to stand around at funerals with a lugubrious countenance. Oliver Twist was of particular service for children's funerals. He would stand near the door of the home in which the deceased's body lay or the church where the funeral took place. Mutes would be clad in heavy mourning, typically black cloaks, top hats with trailing black hatbands, and gloves.