Here in the UK there are lots of schools there are lots of schools aligned with one religion or another. If they get public funding they cannot discriminate between one child and another on any grounds, including faith matters.
This particular school was set up with the goal of having a secular only ethos in which all faiths were treated equally, that is not allowed on the premises. It is quite exceptional though most schools are fairly secular, or have only a nodding acceptance of religious matters. This is not surprising as the Church of England is the largest provider of state education, particularly for the under-11s