I think it's highly unlikely they'll ask "Why?"
The LA guidance does not make any particular form of evidence obligatory:http://www.buckscc.gov.uk/assets/conten ... t_2011.pdf
..... the IAP will then consider any clear evidence from you to support your claim that your child is of the required academic standard.
Examples of this might be a recent school report or a letter of support from their current or previous school, clearly indicating why your child is considered to be of the required academic standard. Marked school work may be brought in on the day of the appeal and the clerk will ensure it is shown to the panel at the end of your appeal before they make their decision. [my italics]
In the unlikely event that you are asked, you can say you thought the panel would be interested in the most up-to-date information available, namely the headteacher's appeal summary sheet.
Obviously, any parent who has
got a good year 5 report ought to submit it because the more good evidence there is, the better!