Around 230 prisoners protested over terrible living conditions and took control of at least two wings of Bedford Prison last Sunday.
The riot forced prison guards to retreat to a “safe place”. It lasted for more than six hours.
Police from across Britain arrived shortly before 5pm. They only reported the situation as “resolved” later that night.
A report by Her Majesty’s Inspectorate of Prisons in May found prisoners in Bedford lived in crowded and cramped conditions.
It also found a dramatic increase in self harm and drug problems among inmates.
One prisoner said inmates were being kept in their cells longer and fed in their cells “like dogs” ahead of the riot.
Mobile footage reportedly taken during the riot showed prisoners celebrating after taking control of one wing.