Tim was a twenty-ﬁve-year old man with a history of serious sexual aggression against male and female children. At the age of ﬁfteen he was convicted of the rape of a twelve-year-old girl, for which he spent two years in youth custody. Within a year of release, he carried out a series of indecent assaults on two twelve-and thirteen-year-old boys. Following conviction for these oﬀences, Tim was admitted to an acute, low-secure hospital facility under sections 37/41 of the Mental Health Act (1983) on the grounds of ‘mental impairment’ as deﬁned within the Act. Tim had a measured full-scale IQ of 77, which placed him in the ‘borderline intelligence’ range. He had attended mainstream school until the age of ten, when he was transferred to a local special needs school because of his learning diﬃculties.