Cheers - so officially what are they expecting the signaller to do all day?!
As others have said, there’s lots of things that aren’t banned - reading*, model making, welding (yes, I know of at least one example!), cooking (I used to quite regularly spend an afternoon at work cooking a big pot of something - dinner sorted for later in the shift, and something to take home for the whole family the next day too), painting - the list goes on.
Although radios are now officially permitted in smaller, relatively quiet boxes, there’s so many stories about televisions and (before that change) radios. My favourite was the manager who turned up at a box to do a visit, knowing full well that the signalman would’ve hurriedly thrown his portable television in the cooker, out of sight, as he approached. The manager triumphantly announced that he’d brought a pie that he’d like to warm up, turned the cooker on in preparation, and then sat and waited!
* - excepting “reading the Rule Book”, which is invariably done through the medium of dreams.