It made me wonder how often head teachers attend overqualification appeals to oppose the applicant. What happens if the head of the school is actually sympathetic to your case, and feels that your child - as a sibling of one of their own pupils - should have been given a place, but has fallen foul of a change in LEA rules over which the school has no control (assuming it isn't a foundation or VA school)? In other words, do they still have to attend the appeal because they are expected to? Or can they take a neutral stance by refraining from opposing the appeal in person?
Imagine the scenario - parent goes to appeal for younger child for a place at elder child's school and must face the head from said school. Someone they probably know and have talked to in the past at school events, or possibly even collaborated with on extra-curricular projects. This would surely place both parties in a difficult position?
It shouldn't be a 'personal' thing on the head's side. At our panel, it's the schools admissions officer who represents the school, and I know that she's quite friendly with some of the parents, often telling them to appeal! And the schools side of the argument is the same for each child appealing - that the school is full.
If you know that they can fit more in, then it's down to you to get them to admit that, and it should be easy if it's blindingly obvious. But what you're then up against is telling the panel why it should be your child over and above the other appeals.