Philipp, Barry Walker used to do new ones, so my guess is that The MG Automobile Company can supply them. I was going to post a link however when tried, it seems the site is being updated and cannot be accessed at present.
Dave, I was thinking the same thing... last week I was in contact with Peter Johnston of The MG Automobile Company. He says there are no on stock at the moment. Andy King sold me one last year, but that was not correct for a P-Type.
Garry, I can not send email, I get an error 550 (Recipient Invalid). But you can contact me directly at philipp.gruber@gruber-informatik.ch to send a photo.