During the summer I researched a little about Mummers, Morris dancers and other English folk traditions for a scene we had in our film.
These pictures of an early Mummer costume from 1829 come from the Cora Ginsberg catalogues I mentioned yesterday.
There is a good book with plenty of reference material for current folk celebrations called Mummers, Maypoles and Milkmaids by Sara Hannant and an excellent BFI collection of very early film footage called Here's a Health to the Barley Mow.
I can recommend both.