Antiquities Discovery Law, UK, Effective?

In the US AFAIK, There isn't any system of monetary reward that allows someone to report and turn in finds without them just being confiscated, in some cases they have confiscated the find and then hold them responsible for taxes, even though they didn't get anything for the item.

There is no incentive for anyone to turn anything of exceptional value into authorities. The following illustrates why we need one badly. { I'll keep it short, as the whole story is very long]

   In the early 70's I lived outside of Phila. Pa. A neighbor, who was a well known amateur Ornithologist and all around interesting person, who attracted equally interesting people called me over to his home one sat. Said he had something I might be interested in seeing.  Upon entering his kitchen I was introduced to a man, 60 ish, average looking, who was sitting by 2 cardboard boxes. After a brief exchange of greetings I was asked to examine some of the items in the box closest to me. I hadn't been told anything about what I was going to see, so when the man handed me a silver chalice about 9 inches tall, still with the oxidation on it, I damn near fell out of my seat.  The piece hadn't been cleaned yet and it was difficult to make out anything on it but it was heavily chased. For the next half hour I saw one amazing thing after another, some of it was Celt no doubt in my mind at all. The guy said "he found it near a stream" thats it, nothing else. I have no idea even which state he was in when he found it.  When I had told him what I thought he had and rough value, he said thank you, gathered the loot and left, I never saw him again.

I wonder how many finds like that just disappear into the antiquities stream every year, and if a substantial reward, tax free from the government  would keep us from losing valuable objects and information.