ha ha at first I didn't get you.Right below your last photo: There is this clicky:
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If you are the vindictive-type ('not even getting a bigMac'...), you can always ""Report" him to authorities... for sale of forgeries.
Anybody who buys a Stradivari at £20K believing it is the genuine article, deserves to be shafted! I still think he was stupid to sell it.
Anyhoo, there are so many copies about, some wonderful ones, that it is a non issue.
The violin was very well-made originally, and sounded very "Big" , and was genuinely old.
BTW good copies can run into million dollars: