An Anglo-Saxcon strapend found by Baz Thugwit up by the Shire Ditch on the malvern Hills is a problematic find. Baz is a coin collector, loves 'is 'ammies. So he'd like to get rid of this strapend to finance his drink habit. But he cannot can he? It's illegal. Oh, but yes he can. He can stick it on eBay and say "Metal detecting from near Shrewsbury", problem solved. What if it were silver? Ooops, treasure. Baz however is resourceful, there's this farmer near Ambridge who's a jolly decent bloke. Baz hands the strapend in to the Coroner for Barsettshire explaing he found it on John Gotland's farm - the coroner buys the story. Simple.
If Britain is serious about tackling illicit artefact hunting and the trade in illicitly-dug artefacts, finders and sellers are going to have to start showing documentation that a find actually was recovered legally in the manner in which they claim. That means valid access and search agreements from the landowner, and it means the landowner has signed over the ownership of individual artefacts to the finder.
This is the only way to deal with the inability to say whether an object was found legally or whether it came from illegal digging on a schedulesd site (like Malvern Hills) or trespassing and theft (Whitstable beach without permission).
[for the slow-on-the-uptake: of course Baz Thugwit did not find an Anglo-Saxon strapend on Malvern Hills because Baz is a literary device, smokes too much so he cannot climb that high, and nobody knows what the hoikers actually illegally hoiked from the site]