I think the statutory guidance is in the Schools Standards and Framework Act 1998 - you can look it up online on the HMSO website.
The numbers on roll for each class size in KS1 should not exceed 30 - however the classes may be organised for certain tasks like the literacy hour so they are more than 30 etc.
Schools are funded so that they can afford to have one teacher per 30 pupils in key stage 1 - they get units of top-up e.g. if a school had 32 pupils they would get 28 units of top-up so they could fund 2 teachers. They do at my LEA anyway.
Which LEA are you talking about - I have worked for a few.