They’ve only been around for a short while and are very rare only a few known. It’s part of the Plaques and Jetons recently acquired. There are 2- £10 Jetons also. Check out the Chipguide they are all listed
David Spragg brought them into the light and into our club when discovered. Very beautiful and historic set basically in my opinion rivaled by none, be hard to out do them. Even though I would put that Penthouse plaque right up there with them that was brought to light as well recently!!!
Thanks
Torrey