Louise Browne sends this picture and adds: "This has been sitting on our heart for the last fifty years or so. My father was an engineer and in the past he was a racer and stuntman. I have no idea what this is. I had thought it must be a radiator blanking cap, but I can't seem to find any brass ones. Is this the real McCoy and did it come from a very early model? It's probably really easy so sorry if I'm a muppet but I would love to know."
Editor: Well if you're a muppet, we are the same. We have no idea how to place this Bentley-London cap, no matter if it's a radiator blank of a hubcap, this one being the closest example we found. So like usual the truth should come from our loyal readers who basically know everything!