I came across this in a google search. I have not had experience with UK schools, but I can tell you about the schools here in the state of Missouri.
I pulled my children from the public school here, and it was not for religious reasons. Even for young children, 5&6 years old, they are expected to sit and work, with one bathroom break mid morning. They have 15 minutes to eat lunch at 11 am, then they are allowed 15 minutes to play during recess until 11:30. Then they go back to work, with no more breaks or snacks. If a child does need to use the restroom they lose points, after losing a certain number of points they lose their recess time.
Then there is the taking their lunch away for unpaid library, fees. It has happened several times here. I am unsure how so many schools in the US get away with this, but they do. In our school the secretary walked in, took a 10 year old girl's lunch away from her and threw it away. Another student tried to buy her a lunch and they refused to allow it, when another student tried to share a lunch, that student was punished by losing their lunch. She got ahold of a phone and called her mother, who came to the school and picked her up.
I am sure every school in the US does not allow this, in fact I have friends in other states that are horrified this goes on here. But our school is terrible, if I could I would move to the UK.