Surfacing Apulian tomb-group in 1981

I have been reflecting on a group of Apulian pots that are said, by A.D. Trendall, to have been derived from the same tomb. All surfaced on the New York market in 1981 and then passed to the same private collection.

Some initial questions. Who provided the information to Trendall? Was it the New York dealer? If so, who provided the information to the dealer? Or was Trendall aware of the source in, say, Switzerland? If this group does not appear to have been known prior to 1970, will the present proprietors seek to contact the Italian authorities?