Almost one in eight prisoners have illegal drugs in their system and another one in five are taking methadone, a jail watchdog has said.
Life behind bars for the 1,260 inmates at Pentonville Prison is "a microcosm of society outside", David Miller, chairman of the Victorian-era jail's independent monitoring board (IMB) said.
Problems of mental illness, drug abuse and educational failure are concentrated and made starkly visible.
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A teenager who was mistakenly released from prison after he was arrested on suspicion of attempted murder has been detained by police.
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