Sail numbers 12446 through to 12526 were issued in 1983.
According to the potted history of the GP14 hull, your one is the very first Fibredon Mk.IV FRP boat, produced in 1983.
Do check that the number on your sail is actually the registered hull number of the boat, which should be permanently marked somewhere, but on that model I am not sure just where; however immediately abaft the centreboard case would seem to be a good place to start.
Once you are sure of the hull number, the Association can let you have a digitised copy of our records for the boat, which will fill in some of her history for you.
Oliver