The Symes Athlete

Athlete from the Schinoussa Archive.
Source: Dr Christos Tsirogiannis

Dr Christos Tsirogiannis has identified a Roman marble athlete from the Schinoussa photographic archive. The sculpture, "A Roman Marble Figure of an Athlete, circa 1st/2nd Century A.D.", is acknowledged as "perhaps acquired from Robin Symes". The photographic evidence can now confirm this part in the statue's history. 

The sculpture is due to be auctioned at Sotheby's, London on 3 July 2018 (lot 23). The estimate is £30,000–£50,000. The stated history is as follows:

• John Hewett (1919-1994), London, perhaps acquired from Robin Symes 
• James Freeman, Kyoto, probably acquired from the above in the early 1970s 
• acquired from the above by Willard and Elizabeth Clark on December 21st, 1980

Tsirogiannis has observed that the statue in the Schinoussa archive is "uncleaned and unrestored, since soil encrustations are obvious on its surface".  Note also the damage to the right thigh.

Did Symes sell the statue to Hewett? Or did Hewett sell it to Symes? Or did Symes sell the statue to Freeman? Or did Hewett sell to Freeman? When did these transactions take place?

What is the authenticated documentation that can confirm the statue's history? When did it surface?