And I've just posted something on the other thread!
A PAN of 40 suggests a capacity of 280, so if there are that many on the roll they are almost certainly full to capacity. However, there are two net capacity figures - the calculated net capacity (which is based on the number and size of classrooms and some other factors) and the agreed net capacity (which is the one they actually use to set the PAN). The calculated capacity is expressed as a range, e.g. 280-310. The agreed net capacity may be at the bottom of that range. If it is, that may help you a little at the appeal if you can get the figures from the LA. Try to get those in advance, though, and only introduce them if they help. If it turns out the calculated capacity is 252-280 then keep quiet about it!
I'm left a little confused as to how many classes they are actually operating. If they are full to capacity and they only have one class each in Y3 and Y4, those classes will each have 40 children. That's pretty big. With 160 children in Y3-Y6 I would hope they've got at least 5 classes. That would work provided several of the classes are mixed.
The fact that they aren't answering your questions is worrying. I can only speculate as to why. However, they should provide a full class arrangement in their papers for the appeal. This will show exactly how many classes the school has and how they are organised. In the meantime, put your question in writing (email will do) and make it clear you view this as essential information to allow you to prepare for the appeal. Under the Appeal Code paragraph 2.12(b) the LA must give you all the information you reasonably ask of them. This must information must be supplied to you at least 3 working days before the hearing. It would be very difficult for them to argue that a request for the class arrangement was unreasonable.
Whilst it is obviously useful if you can show that the school can cope with extra children, the fact that there are 11 children appealing suggests you are unlikely to win in stage 1, although it obviously helps if you can show that the school can cope with one or two more children. If I were you I would do what you can to attack the LA's case in stage 1 but concentrate on stage 2. That's where this appeal will be won or lost.
If you do get a class arrangement and/or the calculated net capacity I might be able to give some further ideas (but no promises!).