Hi Kestrel
AFAIK the reissue process I described above will work even if your FAA certificate is the old expired paper one. You will need to take the certificate to LGW, together with the other documents, so they can verify the number and quote it to the FAA.
If you want to be sure you can call Ms Tona Gates, the manager of the Airmen Certification Branch, on +1 405 954 3822 or e-mail her on
[email protected]