Dear Rainbow mum
I'm uneasy about the head's comment at the appeal (your son "would not cope in a grammar school environment based on his results though he's above average"). If I had been on the panel, I would have asked "Does the school not have any special needs provision?" If he felt unable to answer the question about what would have happened if the school had known about the visual & motor skills problem, is he any more qualified to comment on how a bright boy (top 1%, numerical reasoning) might cope, given the necessary support? We don't know how strongly the panel were influenced by the head's comment, or whether they took into account any special needs provision, but it might be worth trying to get access to the clerk's notes to see if they shed any light:
http://www.elevenplusexams.co.uk/11plus ... ers.php#d4
For what it's worth, as far as I can tell, I think you have quite a good case. The outcome of these appeals, I suspect, has more to do with how strict the panel are, rather than anything you do.
The odds are against most appeals succeeding, but your son should be proud of how well you are representing his interests.