My question is should my appeal letter include details about the reasons for the CAF being late or should it focus solely on reasons why he should get his first choice school? If both which is most important/should I mention first?
Both - I would start with the CAF, not because it's more important, but because logically admission arrangements come first.
It could be difficult to argue that the admissions clerk acted incorrectly, so the best approach would be to appear very reasonable (almost apologetic) and say "I would respectfully ask the panel to please take into account the extenuating circumstances that led to the loss of a place
". It would be best if you can provide some evidence.
Even if the panel decide the admission arrangements have been correctly applied, with any luck they may be sympathetic to your plight, which might help when they come to consider your reasons for wanting a place.
Try to get the balance right - aim to write as much about reasons for wanting a place as about the CAF. Preferably more!http://www.elevenplusexams.co.uk/appeal ... -school#c2