When Britain's biggest prison opened its doors in 2017, it was hailed as a £212 million model for the rehabilitation of offenders. But just seven years later, HMP Berwyn in North Wales has acquired a very different reputation — as the epicentre of a sex scandal engulfing the Prison Service.

Last year it emerged that no less than 18 women working at the Category C 'super-prison' for adult males, with a 2,100 capacity, had been sacked or resigned after breaking the rules on relationships with inmates.