Tablet pouch

For safety purposes on single track railways the train driver had to have in his possession a token to allow him to proceed into a particular section to ensure that no other vehicle was also in this section.  

The token was contained within a pouch like this one with a large handle to make it easier to hand over the token without needing to get out of the locomotive cab.  This particular pouch was used in British Railway days on the Highland Division, where single track lines are particularly common.  

The system now in use in the Highlands is a development of this system, known as Radio Electronic Token Block in which a radio signal transmits a ‘token’ displayed in the cab.