I think the easiest way is through the GRO main office. You can do it online and pay with your credit card - here :
http://www.gro.gov.uk/gro/content/certificates/You can also order through the local office - you can find the addresses online - Barnstable is here :
http://www.devon.gov.uk/north_devon.htmIf you use the local one, not all of them take payments online, if they don't, you will need to send a cheque and a stamped addressed envolope. Also, because sometimes the registration areas change - it might be better to ring them first just to make sure they hold the certificate for that year.
Good Luck - let us know the details when it arrives and we can help you get back a bit further.
Maggie
There's no place like home ......