Hi All too much,
2 of my 3 children at GS got in with the pass mark, (one of which was helpfully rounded up to reach the pass mark - for which we were eternally grateful - ours was an average score on 3 papers). One of them was embarrassed, I think at the time of going, in case she wouldn't be good enough! What nonesense, she is now in yr 12 and doing very well indeed - her GCSE results put her in the top half of her cohort, and she will (fingers crossed) do very well in her A Levels.
Every child is different, and I think that the scores on the day really bear very little resemblance to how the child will do in the end. I have known friends of my children who got very high scores in 11+, but failed to do anywhere near as well at GCSE, so the most important thing is for your child to not worry at all about the fact they got in on appeal - the fact is that your son just underperformed on one day, and that's the end of the matter.
He will, I'm sure do very well, and I don't believe the teachers will pay too much attention to actual scores once he is there and working well.
I hope this helps,