They've rewritten the law. I think everyone is happy now.
THE TIMES SATURDAY AUGUST 22, 1998
"...ARCHAEOLOGlSTS are reaping a golden harvest following a truce in their war with Britain's army of metal detectorists. After logging detectorists' finds in six trial areas for just under a year, they have recorded thousands of objects which previously would have vanished into private collections. These include artefacts which have rewritten the history of the British Isles, as well as mundane objects which reveal more about ordinary lives than any number of history hooks.
If I recall correctly, the 1998 law says that the government must pay finders market value on items declared Treasure Trove.
I don't know the tax status of such payments, though.