Headcodes

Headcodes are an indication of an engine or train's class or importance by means of a position of lamps shown on the front of an engine, or white discs during the day. The headcode system allows the signalmen at the signal boxes to identify and regulate trains and determine their routes.

Engines on the North Western Railway have been seen wearing lamp and disc codes on many occasions in the Railway Series. According to Surprise Packet, the NWR has its own headcode meanings.

In the television series, the engines no longer used headcodes with their lamps following the third series briefly until the sixth series onwards. By the request of railway consultant Sam Wilkinson, all the engines eventually gained permanent lamps from the seventeenth series onwards, with the Branchline (Toby, Rosie and Nia) and Empty Wagon (Thomas, Edward, Henry, James and Percy) headcodes being the most common, though some engines have a random arrangement of lamps.

Although headcodes are not used in the series anymore, some engines have been permanently fitted with the express headcode, them being Gordon, Spencer, Flying Scotsman, Lady, Merlin and Lorenzo, the most recent being Duchess.