An Unrecorded Hoard of Third Century Coins from England

On the Moneta-L forum, Curtis Clay reports that Hubert Lanz supplied the following information about the first Proculus coin which  is now in the Staatlichen Münzsammlung, Munich. It was sold in Munich in 1991 for DM 92,000 (Bankhaus Aufhäuser Auction 8, 9-10 October 1991, lot 640) :

Dr. Lanz responded that that first specimen had a very convincing provenance: the British coin dealer Richard Swan, who lived in Munich for many years, "got it from a large lot of late Roman Ants found in England which he cleaned". Reply #40 on: November 16, 2012, 05:26:56 pm »

The two known coins of this ruler were therefore both found in England and are from the same pair of dies with the possible traces of the Trier mint-signature. So where was this group of antoniniani which arrived on the German market in 1991 from?

The context of this is that this group of coins "surfaced" about the time when there was a debate (I use the term loosely it was the period called the Detector Wars) over new laws to cope precisely with such finds - eventually to surface as the treasure Act, not without a huge amount of opposition from artefact hunters anxious to protect their "rights", this coin ending up surfacing on the market from goodness-knows-where is precisely the result of the lackadaisical approach to metal detected finds that existed for most of the period when the hobby was getting established. And what, pray, is wrong with the notion "STOP Taking Our Past" when we see things like this happening? And where are the rest of that "large lot of late Roman Ants found in England" now? Can ANY of them be identified as such?