Yesterday morning I let my six hens out of the coop. Late yesterday afteroon, I found seven. Number Seven is a beautiful little hen in full plumage, a bright, rich russet head and body, with a black tail. Short and cobby, with an upright tail, white legs, regular comb. Leghorn? Sorry, no photo capability.
Leghorn have yellow legs rather than white, im thinking old english game bantam is a possiblity. Japanese bantams and seramas both have yellow legs too.
My first guess would be that she's an Old English Game or a mix of OEG. They have white skin, and tend to be the most commonly found "wild" chickens because they are hardy and can survive well without caretakers.
The gamebirds are waaay too long, front to back. This one is as short in that direction as a chicken can be. And her tail is the shortest upright type, and looks like someone just dipped her whole tail in black paint. I went through Google Images for both game hens and bantams, and nothing was very close. So I'm assuming that she's just a very pretty little mix. I don't think I've ever seen a chicken that SHINY -- very healthy-looking feathers. My Columbian Wyandottes are making faces at her and calling her the "runt", so she's been hanging with the Ancona ducks.