The Code states:
2.15 Representatives of the schools being appealed for must not support individual appeals at the hearing itself or by providing letters of support for appellants, because of possible conflicts of interest and the possibility of unfairness to other appellants.
In my view the panel were right to treat the evidence as inadmissible.
Ideally, the clerk should have notified you about this in advance, and I suspect this would have happened if you had actually included the letter with your submission. Whether the ombudsman would regard this as so serious as to amount to maladministration is another matter.
With regard to the Review, I think there are grounds for going to the ombudsman if any panel refuses an appeal on the basis that there has been a proper review, but parents have not
been informed in advance that this is to be a key issue, or the authority's case makes no
attempt to justify the review as being fair/consistent/objective.