Yes, cut in to sandstone in a cliff face near the river Trent. I visited it a few years ago. Needs a bit of fixing up and a coat of paint. It is only a couple of miles from Repton, which used to be a big royal site for the kingdom of Mercia. Possibly the former Northumbrian king was exiled there so the Mercians could keep an eye on him? Quite a common thing throughout history for a deposed king that it wouldn't be politic to kill to be exiled to another country and kept under observation. Some decades later the whole area got invaded by Vikings who sailed up the Trent from the Humber estuary and spent the winter at Repton, which was the end for most of the Mercian royal family. Location is https://www.streetmap.co.uk/map?x=433929&y=327200&z=120.