I plan to comment on the withdrawn objects from Christie's in a little more detail. I note that a spokesperson for the auction house has called for access to the Medici and Becchina photographic archives. But this misses the point that at least one of the pieces appears to feature in a published consignment list. Surely the register used by Christie's to check for stolen items would have made that link ... But it appears that they are unfamiliar with such literature.
It goes back to my earlier point that the auction house needs to adopt a more rigorous due diligence process and that may mean changing the agency used to check collecting histories.