See http://richardedmondsauctions.com/catalogue-new/?event=2 – there it’s catalogued (lot 427) as half a propellor blade, brass edged and tipped, with a guide price of £30-40. Perhaps more interesting is the preceding lot which is catalogued as: ‘a Bristol Cherub two blade wood propeller, fully stamped to the boss, 55 1/4″ long, with accompanying photocopied brochure describing the Bristol Cherub Series III air cooled aero engine’ with a guide price of £300-400. The auction appears to be taking place tomorrow.