So sorry to learn your news. Very surprising that your son was not given the extra time he needs to demonstrate his ability.
Feel so angry on your behalf
about the LEA attitude. Did they put this in writing about appealing afterwards (bet they didn't).
Unfortunately the world does need to wake up to the fact that you can
be really bright and also have special needs.
Hope this link helps:
http://www.nfer.ak.uk/research-areas/as ... -ranks.cfm
Our selective consortium in Herts awards extra time (up to 25%), some interesting posts under the Bucks section about this also. Have a dig around on your LEA website too about disability discrimination/special needs etc and see if you can find anything.
Very likely you would need to supply professional reports as evidence, Educational Psychologist for Dyslexia and Occupational Therapist report for handwriting. If you have these already use them for your appeal.
Hope this helps.