How many primary schools in England are over capacity?

Post: 13 January 2015

Today the Guardian reported on findings from a Labour Party study of primary school places in England. The study, based on Freedom of Information requests to local education authorities, found that 18% of schools were over capacity, with another 9% at capacity.

I haven’t been able to find any more detail on this study, but I’m puzzled: why did Labour rely on FOI requests when information on both capacity and number of pupils is available, for individual primary schools, in the Department for Education’s open EduBase dataset?

I took an extract from EduBase today and pulled out the data for primary schools in England. This is what the stats look like, based on a comparison of the [SchoolCapacity] and [NumberOfPupils] fields:

Based on the above, the percentage of primary schools that are over capacity is rather higher than 18%.

If we just look at community schools, i.e. the 8,000 or so state-funded primaries where staff are employed by the LEA, the numbers are even worse:

So what am I missing? Were the FOI requests based on some other definition of “over capacity”, or has Labour missed a trick?