I would have though it's pretty unusual to see non-passenger stock left in platforms open to the public for any length of time, but a rail grinder - at least I assume it is one as it's fleet number appears to be simply "RDG" - has been parked up in Moorgate platform 4, a Circle bay, for the best part of a week now with NOT TO BE MOVED signs. If it's seized up, it's going to be rather tricky to rescue!