Staff were filmed hitting, kicking and leaving special school pupils in their own urine, the BBC has found.
Despite the school proving abuse in so-called "calming rooms", some staff are still employed there and have not been barred from working with children.
Parents say they have not been allowed to see the footage and were misled about the use of isolation.
Whitefield School said it acted in pupils' best interests and was not obliged to make barring referrals.