I'm unsure why you handed it over. I would not have. They have no legal right under the Treasure Act unless its deemed to be of significant national historical interest. (One of the grey areas) Or it was from a ritual site which is another grey area. It is over 300 years old but it has no silver or gold content (or at least not 10% or more), so they can only record it under the PAS & return to finder. If you want it back & you have an agreement with the landowner, go get it. I assume you still have the PAS Receipt?