Before World War I, Walter Owen Bentley, and his brother, Horace Millner Bentley, sold French DFP cars in Cricklewood, North London, but W.O, as Walter was known, always wanted to design and build his own cars. At the DFP factory, in 1913, he noticed an aluminum paperweight and thought that aluminum might be a suitable replacement for cast iron to fabricate lighter pistons. The first Bentley aluminum pistons were fitted to Sopwith Camel aero engines during World War I.