Looking from Soaper Lane railway bridge. The number of this engine is 73139. Therefore it is a British Railways Standard Class 5 engine. Note the oil-lamps on the front (painted white), one above each buffer. This is the 'Headcode', and this configuration shows the engine is hauling an express-passenger train. The given location identifies this as the Midland Main Line. This is a non-standard member of its class. In practice, the formal name for this class was shortened to 'BR5'. Engine no. 73139 was one of a batch of 30 of the class fitted with Italian designed 'Caprotti Valve Gear' to try to improve performance. The difference between this and a conventional member of the class was easy to determine with a glance at the engine's wheels, as it involved an alternative method of applying power to the driving wheels.