Bringing up the rear...

"The Muriels of Blackheath" - a bunch of girls (usually more than on this occasion) who turn up to parades in wedding dresses (mostly!) and gorgeous masks.

I think it's safe to assume that "Muriels" is an allusion to the 1994 Australian film Muriel's Wedding.

See if you can spot Cymbeline in the Pool Park Action Day group, just ahead of them.