The majority of backbench Labour MPs did not expect the huge numbers of school closures & the tens of thousands of migrating children, especially SEND children.
The initial tax gouge on a hostage cohort, mid budgeted year, is now declining in its second year leaving the Treasury with the headache of spiralling costs & diminishing revenue, precisely the conditions it imposed on independent schools forcing them to close down.
The backbenchers have a choice, lose their seat or rescind the tax.