If you need a certificate for registering a vehicle in the UK then the BSA Owners Club or the VMCC are the correct routes.

For other countries, or for information only, the certifcate that Henk Joore supplies is probably more informative.

http://wdbsa.nl/BSA%20Dating%20Service.htm

The same e-mail is used as that linked to any Paypal donation :- ahum@quicknet.nl