A prison’s attempt to reduce high levels of opiate prescribing resulted in an “unsafe” drug treatment regime which led to inmates being put on suicide watch and others at risk of overdose, a report by the prisons watchdog has revealed. The findings by HM Inspectorate of Prisons into events last year at HMP Wayland, a category C jail in Norfolk, will send a stark warning to Britain’s prison estate of the problems associated with weaning inmates off heroin substitutes too abruptly.