Screw propeller from type-23 frigate, on display in Neptune Court. Made of nikalium alloy (nickel, copper, aluminium and manganese), this was manufactured by Stone-Vickers Ltd and is in the Museum partly because it was rejected for service as not exactly meeting the technical design specification: according to former employees at the firm the blade edges had been ground a little too thin. Josiah Stone established a foundry in Deptford in 1831, of which the non-ferrous works subsequently moved to Charlton in 1917 and became J. Stone and Co (Charlton) Ltd in 1951. Its Marine Department produced the propellers for the 'Queen Mary', Queen Elizabeth' and RY 'Britannia' among others, and 22,000 propellers for the Navy during WWII. It also made variable pitch propellers and water-tight doors (inc. for the 'QE' and RY 'Britannia'). The General Foundries produced specialized alloy castings for industry and aircraft propellers and other parts including for the 'Viscount' and 'Comet'. Stone foundries still operates at Charlton but mainly for the aircraft industry. As Stone Vickers the firm was incorporated as part of Rolls-Royce Plc. [PvdM]