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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Before the final declaration on Friday, the Conservative candidate looked set to lose the City Hall race to Labour's Sadiq Khan.
The Tooting MP has been the frontrunner in the counting process ahead of Tory challenger Zac Goldsmith.
It's not just London where elections have been taking place today. There were council elections taking place across the home counties.