Just realised there are two threads. As most responses are here I am reposting my response from the other thread. But please read this. I'm afraid some of the responses on this thread are misleading and I have added to my response as a result.
As they are below PAN in the year an appeal has a good chance of success. The problem in September clearly comes about because they have admitted beyond PAN in Y4. The fact that the class will be even bigger next year is a point in your favour.
The first point in your appeal should be that they are below PAN in the relevant year and therefore they should admit your daughter as there are places available. You should also point out the numbers next year to counter their argument about what happens in September.
You should also explain why your daughter will be disadvantaged if she doesn't attend this school. Don't be negative about her current school unless you have documented evidence of the school failing to meet her needs, e.g. not taking effective action against bullying. Concentrate on the positives of the school you want.
Turning to comments on this thread, there appears to be confusion about PAN. It is NOT a whole school number. There is no such thing as an overall PAN for the school. PAN is the number that will be admitted to Reception in the normal admissions round. Technically PAN only applies to Reception but it is normally regarded as following the year group as it progresses through the school. For most schools PAN is the same for all years but it can be different if, for example, the school had a bulge class in Reception one year. For this particular school it sounds like PAN is 15 for all years.
There is a number for the whole school but that is called net capacity, not PAN. It is the number of pupils the school can theoretically accommodate based on the size of the buildings. If the school is over capacity it gives some strength to their argument but not much if they have created the problem themselves. An appeal panel should take the view that when the school admitted beyond PAN in other years they should have anticipated and planned for any problems that would be caused if any years that were below PAN at the time filled up to PAN. In general a school cannot refuse admission to a year that is below PAN.
I agree with Admission on your original thread. It seems unlikely that the additional pupils in Y4 and Y3 were all admitted on appeal so the school has created its own problem by admitting substantially beyond PAN in those years. That means an argument that they should not admit to Y5 when it is currently below PAN is quite weak. Unless there is something we are missing here I would be pretty confident of success in your position.
As far as I can tell the year 3/4 class has 41, unless they have held some back into year 1/2 .... could they even do that can keep juniors with reception
They could teach Y3 pupils in a Y1/Y2 class provided there are no more than 30 in the class overall. It is worth checking (and you should also check to see if they have put any of the Y4 pupils in the Y5/Y6 class) but I suspect you will find that the Y3/Y4 class has 41 pupils.
You're assuming that the numbers currently in Y4 and Y5 will flow through to a Y5/6 class of 41 children in time. There's been no indication in their communication that this will actually happen
Unless the school says that something else will happen and has made decisions as to what that will be the OP and the appeal panel must assume that the 41 pupils currently in Y3/Y4 will become a class of 41 in Y5/Y6. It is likely that they are already a class of 41 if there is only one Y3/Y4 class.
usernjdhkvdgkb - If you are having trouble wording your appeal feel free to PM me. I will be happy to take a look at whatever you have written and suggest improvements. If you PM me it would be helpful to know the name of the school and the LA.