Head Code

A visit to the National Railway Museum always turns up something interesting. This light on one of the locomotives for example was not used to illuminate the track ahead, but to act as a code light so the signal man would know what type of train was approaching. Thus a passenger train could be distinguished from a freight train, and even the type of freight, livestock, perishable goods etc could be indicated.
Incidentally there is real threat that this museum could be closed in the next couple of years due to a government reduction in funding. If you feel this should not happen you may be interested in signing a petition here