The practice by maintained secondary schools of selecting their intake of pupils, or (previously) of that selection being carried out by the local authority through a process of testing pupils at Eleven Plus. Following the Education Act 1944 (Butler Act), pupils were selected according to ability to go to the type of school considered best suited to them. In most local authorities this system of selection was replaced in the 1970s by a system of non‐selective, comprehensive secondary education, following the Education Act 1976. However, the policy of selection for secondary schooling was enabled to continue in some areas because the 1976 Act was superseded by the Education Act 1979, which made the abolition of selection optional rather than mandatory. It has been argued that the practice of selection at the age of 11 continues, not only in those areas where grammar schools remain, but also as an inevitable result of market competition within the schooling system, which has caused successful schools to become oversubscribed and therefore enabled them to operate some degree of selection over their intake. Moreover, the specialist schools introduced in the 1990s are permitted to select up to 10 per cent of their pupil intake, based on testing of aptitude for the specialist subjects, rather than on ability, and thereby echoing the aims of the earlier tripartite system.