A school where pupils allegedly chained a black student to a lamppost and whipped him in a "mock slave auction" has been rated as inadequate by Ofsted.
Police investigated a racially aggravated safeguarding incident at Beechen Cliff School in Bath in January and interviewed seven boys. Ofsted found staff failed to report the incident and their response to it was "insufficient and too slow".
The chair and deputy chair of the board of governors have resigned.
The Ofsted report follows an unannounced inspection in May which found safeguarding at the school was "not effective".
Inspectors said the language used by leaders and governors during the inspection to describe the incident gave "serious cause for concern".
"They still do not appreciate its true gravity and little appears to have been learned from the way that this issue was handled, as the ongoing poor practice with regard to referrals demonstrates.
"The school's current plans to improve safeguarding are weak."
The school, which has over 1,300 pupils, was previously rated outstanding in 2014.
