Well, you've instantly added value to it, as I bet the seller hasn't a clue. The best I could manage was a BR 21t coal hopper wagon plate, bought at the SVR, principally because it was made at Shildon, where I had the privilege of seeing the vehicles constructed. The drop forge was a wonder to behold (and hear). Anyhow, thread drift... let's get a few of these mining and transport artefacts back to their rightful places.
Alec