Confused about masks in schools

[fizzypop100]

Received an e mail from secondary school yesterday to say that masks are still required. Boris today says that schools can't do this. Who is right?
School Yes
Boris No.

If the guidance / law says they are not required then they are not required.

Surely schools can make their own rules, though. There's no "law" saying that pupils must wear blazers, but some schools make their own rule that blazers are compulsory.