The guy was a trainee at Clifford Chance... then he was let go. He worked for a bit as a tax consultant at E&Y... then let go from there too. So he blatantly still had the opportunities regardless of him getting a 2:1 rather than a 1st - if he's trying to blame his lack of success on depression etc.. then fair enough/whatever but to try and boil that depression down to a single event/result in his life is ridiculous.
You can't sue your depression for 1mill.
Come to that he probably can't sue Oxford University for 1m either but it's more realistic than suing yourself.