A new BBC documentary is shining a light on the drug epidemic in HMP Barlinnie, Scotland's largest prison. Home to around 1500 men, it's so severe that 80% of inmates are estimated to have a narcotics problem. Opened in 1882, the Glasgow jail - where inmates are serving time for crimes from murder and assault to theft and sexual offences - has held some of the country’s most notorious criminals, including serial killer Peter Manuel, gangster Jimmy Boyle, and Lockerbie bomber Abdelbaset al-