A self-styled emir meted out justice in HMP Woodhill and radicalised inmates ...

Islamist extremists in Britain’s prisons are holding makeshift Sharia trials, circulating banned books and openly grooming young Muslim inmates, The Times has been told.

A former prisoner who claims that he took part in Sharia courts and punishment beatings has given a detailed account of how he came to join a group of prisoners at HMP Woodhill, Milton Keynes, who pledged allegiance to Isis.

The revelations have prompted security experts to call for a fundamental review of terrorist radicalisation in jails across Britain.

The issue came under scrutiny last month when Usman Khan, 28, a Category A terrorist prisoner freed on licence, murdered two people at London Bridge before being killed by police.

Richard Walton, former head of Scotland Yard’s Counter Terrorism Command, and Ian