"The Crown had a prerogative right to treasure trove, and if the circumstances under which an object was found raised a prima facie presumption that it had been hidden, it belonged to the Crown unless someone else could show a better title to it.[25] The Crown could grant its right to treasure trove to any person in the form of a franchise."
So you didn't dig through the records to see if they have been seized. It belonged to the crown unless you could find reason why it should not. If there was no clear owner, it was presumed to be owned by the crown.
That was back in the 19th century and earlier though.
From around WW1 it became default practice to pay the full value if a museum took it, or return the items to the finder if not. The 96 act added nuance and the split with the land owner. Mainly, I think, thanks to detectorists finding stuff on land that was someone else's.
"The Crown had a prerogative right to treasure trove, and if the circumstances under which an object was found raised a prima facie presumption that it had been hidden, it belonged to the Crown unless someone else could show a better title to it.[25] The Crown could grant its right to treasure trove to any person in the form of a franchise."
So you didn't dig through the records to see if they have been seized. It belonged to the crown unless you could find reason why it should not. If there was no clear owner, it was presumed to be owned by the crown.