Locomotive boiler plate, gunmetal, circular, embossed ‘Yarrow Gresley High Pressure Boiler Patent Reg No. 303284 1928’, ex London & North Eastern Railway W1 4-6-4, No. 10000, ‘Hush-Hush’ locomotive, the discarded boiler plate was rescued by Frank Heslop who was an apprentice at Doncaster Locomotive Works in 1936 when the locomotive was rebuilt with a conventional fire-tube boiler, thought to be the only surviving part of this experimental high pressure steam boiler that was eventually scrapped in 1965.