Very cool! Clean it gently... Soak in a gentle acid such as ketchup or coca cola for a day or two, then brush with an old toothbrush... Then another photo, perhaps?
Whatever it is, I don't think it's a head badge. There's a design there, but I can't quite make it out. Yet.
I have cleaned it already, thats the best it would clean
it has remains of green paint on it, the design is a rooster stood on a wheel, a scroll saying "Clement" is in front of the rooster. I've found the company, but it's a French company, I can't find any of their bikes that were made in Britain. It does say "British made" on the badge though