The film-maker Rex Bloomstein, who pioneered a British prison television documentary, gains unprecedented access to the largest sex offender prison in Europe, HMP Whatton in the UK. Since the revelations surrounding high profile figures in the UK entertainment industry, there are more sex offenders in English and Welsh prisons than ever before, around 11600 out of a total population of 86000.

HMP Whatton, with its capacity of 841 prisoners, is a specialist treatment centre for sex offenders – 70% of whom have committed offences against children, the rest against adults. Bloomstein explore the methods used to get prisoners to confront their offending behaviour and to prepare them to go back out into the world. Their re-offending rate, 6%, is surprisingly low compared to 50% for the general prison population.

Bloomstein then travels to the Netherlands to examine how it manages men who have not committed contact sex offences, that is the downloading of child pornography, in the community. He gains access to the clients and staff at the clinics of de Waag, the oldest and largest centre for outpatient psychiatry in the country. He discovers that the Dutch police often refer men who they arrest in possession of child porn straight to de Waag before they go on to trial.

Bloomstein also hears about the work of the helpline Stop it Now!, which through its publicity campaign, aims to encourage men with a sexual interest in children to come forward for treatment before they commit an offence.

(Photo: Indian police officers escort Ravinder Kumar, who is accused of murdering and sexual assaulting a six-year-old girl, 2015. Credit: Sajjad HussainAFP/Getty Images)