 The Leader was the first steam locomotive to use a form of sleeve valve since Cecil Paget's locomotive of 1908 and the concurrent testing of the principle on "Hartland Point" hints at the rushed nature of the locomotive's conception.The locomotive sat on the unusual Bulleid Firth Brown wheels, which were lighter, yet stronger, than the spoked equivalent.The use of sleeve valves and oil baths to lubricate the moving parts of the engine units was inspired by contemporary internal combustion engine practice.