I was able to view this piece recently but foolishly did not take a record of the lozenge and now I can't read it. I think it could be a Thomas Webb reg from 1870 or possibly an earlier one from Hodgetts, Richardson, Pargeter. It is difficult to tell as these registrations appear to be based on the prunt (legs) - and they look pretty similar on the various registrations.
Dimensions are H 2.5in and W 3in
I don't think this has come up on the board before, can anyone id it for sure?