The B.66 is usually marked "Gent's Model." That's the super wide one Neal refers to.
"Champion" is the racing saddle shape. B.17's are labeled either "Champion Standard" or "Champion Narrow." What you have, obviously, is a saddle with the shape of a B.17 standard, but with the springs of a B.66.
I believe this model was later renamed "flyer."
Isn't the Champion Flyer a single rail saddle?