Symes and a Roman medical set

Top: medical set for auction in Paris
Bottom: image from Schinousa archive

Pierre Bergé & Associés of Paris are offering a rare Roman bronze medical set (16 May 2018, lot 236). Its recorded history is: "Ancienne collection Hishiguro, Tokyo, 1992". The catalogue entry helpfully informs us that the set probably came from a burial ("Cette trousse de chirurgien a probablement été découverte dans une sépulture ...").

The set appears to be the one that has been identified by Dr Christos Tsirogannis from an image in the Schinousa archive thus linking it to Robin Symes.

Given that the catalogue entry suggests that this piece came from a funerary context and that the history of the piece can only be traced back to 1992 (and not to 1970), questions are being raised about the set's origins.

What due diligence was conducted on the medical set prior to offering it for sale? Did Symes sell the set to Hishiguro? How did Symes obtain the set? Who sold it to him?

I understand that the appropriate authorities in France are being informed about the lot.