Update on this - I was the guilty one in terms of wanting legal support (son 's view is that it would look bad and make it more stressful).
We wrote again to the Head and to the class teacher, two weeks ago, but have had no reply whatsoever. Class teacher had previously said that she would be willing to write a letter, and that in it she would make particular points of the fact that GD's English is on the same level as her top GS girl last year, and that whilst she knows GD is very able and GS material, she would be likely to under-perform in such a crucial and emotionally significant test.
However, nothing - we can only conclude that Head has forbidden class teacher to write. Obviousky if this is the case, we can't put pressure on her to do so.
A friend who has been on appeals committees said that if there was no letter from the school, the conclusion he would come to, would be that there was some doubt about this candidate in behavioral terms - i.e. a disruptive influence or just not a nice kid. I can understand this, and it makes it even more galling, as GD is, according to the Head, 'A great girl - very hard-working, lots of imagination, an asset as House Captain and very responsible and kind-hearted.' But she won't put it on paper! Instead, she talks about GD's results when she was 7 years old in KS1 SATS, when she was 'in the top third but not the top 8.'
What can we do? Should we abandon our appeal, since the Head looks set to refuse? We are very upset about this, as GD has been a model pupil and is the only one out of her top set of 8, who did not get a selective place - 5 to GS, 2 to highly selective Indies - and her! We're anxious not to be rash in our plans, so would welcome any advice!