The late Steve Vincent seems to be the voice of some in the collector "lobby". In one of his last pieces ("Ancient Treasures for Sale. Do antique dealers preserve the past or steal it?", Reasononline, April 2005) before his tragic death in Iraq, he quoted the collector Shelby White.
"All we've done is make public and private collections more vulnerable to claims from foreign countries. At the same time, we've made it harder for Americans to see the glories of the past."
She is absolutely right as I presume the "we" refers to like-minded collectors.
So, yes, collectors like Shelby White who have drawn on recently surfaced antiquities to enhance their holdings have made "public and private collections more vulnerable to claims from foreign countries".
She knows it because Polaroids showing some of the objects in her collection have been seized in Geneva.
She knows it because it is reported that the Italian government is seeking the return of selected pieces.
When will she come to an agreement so that Italians can see these glories from their cultural heritage in their own country?