Mono Monday - Old

For the Mono Monday challenge of 'Old' I thought I'd pop down to the William Marriott Museum at Holt Station. The museum houses many artefacts, documents and other bygones from the age of steam in East Anglia. I was in a hurry, so I took a few photos and headed off to the U3A photo group meeting where we had an excellent talk from a guest speaker. When I came to process the photos, I realised I hadn't actually looked at a description of what this object was!!! I know on the Poppy Line they use a token which has to be in the possession of the driver when he leaves so that only one train can pass at any time. I wonder if this tablet system is similar - JohnRH can you help?

Thanks to TheAphid for hosting Mono Monday this month.