Why is that?
If I’d found them, I wouldn’t have reported them either. Must be a “British thing”.
When coins are found in, say, eastern Europe, they wind up going directly into the antiquities markets, whereas in the UK there is much more regulation of such things. Say what you want about the British bureaucracy (stubborn, set in its ways, prideful) it isn’t very often found to corrupt.
A great number of late Roman Empire / Eastern R Empire / Byzantine -era caches are bronzes, and they don’t survive so well in the soil. Some of those “clean ‘em yourself” collections on places like eBay are (reportedly) fakes now, but at one time all or most of such for-sale items were actual concretions of crappy, late-antique bronze coins.
As the western provinces ceased to be functionally under Roman rule, and the power concentration shifted toward the east, Roman currency was mostly in bronze, as the Romans had previously figured out (as have all successful large states) that money is a medium of exchange rather than being something of so-called intrinsic value (iow, money isn’t a commodity, while precious metals are). The Roman Empire hit its all time financial peak with Emperor Trajan’s conquest of Dacia, and that was due to the gold mines and piles of gold loot he grabbed and carted back to Rome.
Despite that, the Roman Empire managed to totter along (joke) in some form or other for more than a thousand years thereafter, until Constantinople fell to the Turks.
The Brits are required by law to report any find and turn over any antiquities to the government. If the government decides that they don’t want to confiscate this find, then they will give it back to the finder. The Brits are so pussy-whipped(much like all the other English speaking people of the world), that they will much more readily submit to government orders than other European nations.
bumped ‘cause I want to know too.