This is the one-handed clock that Queen Elizabeth the first presented to Castle Rushen in 1597.
I have no idea why it only has one hand - you have to judge for yourself exactly how far between any two given hours the hand is pointing. And, to be honest, although it is still the original clockwork - and, I think, the original hand - I'm guessing the face has been replaced more than once. But Castle Rushen is very proud of its clock.
I may post a second response to the prompt, just this once, later in the week - as I mentioned to Caristiona that I think there is one on the island the same shape as the clock she posted, just with a different paint-job. So, if I get a chance, I'll go that way and take a picture.