Mmm... just what I was thinking too. Perhaps it was all of his students over the three years. Even so, it is not the kind of thing to tell a journalist who specialises in that area and could be expected to understand the situation.
I kind of got the feeling that much of what we see in the letter rather directly reflects JA's own interpretation. The letter goes on to say:
“…our client has arranged for his PhD thesis to be independently peer-reviewed by individuals at the University of Cambridge. As part of this review, his thesis has been run thorugh Copyleaks, a similar plagiarism detection program to Turnitin, and it returned a result of 2.6%. Scribber, another similar platform, returned a percentage of 7%. Our client has also processed his PhD thesis himself through Turnitin and it returned a similarity result of 6%.”
These seem to be very low figures given what Nathan Cofnas came up with, and the numerous specific instances of apparent plagiarism that many of us have seen. So perhaps that was just JA's undigested take on the findings?
How can I put it delicately... could it be that it wasn't just Cambridge, loads of other universities, a publishing house and an adoring media that he duped?