People with learning disability form an important group among those arrested by the police. Whilst Robertson et al. (1995) estimated the proportion of those arrested with a learning disability in England and Wales to be small (less than 1%), Lyall et al. (1995), in a sample of 251 arrestees taken to a Cambridge police station over a three-month period, found that 11.5% had received special education and 4.4% had attended schools for children with moderate learning difficulties. Gudjonsson et al. (1993) found the average IQ of 160 randomly selected detainees at two London police stations to be 82; approximately 9% had an IQ below 70, i.e. intellectual functioning within the range of learning disability (WHO, 1994) with a further 42% functioning in the borderline range.