In 1965, the London Government Act 1963 came into force, transferring Chis and Sid from the county of Kent to the newly created Greater London. Now part of the London Borough of Bexley, it lost access to three quarters of its former catchment area, which remained under the jurisdiction of Kent County Council. Further change came under the Labour Party government of Prime Minister Harold Wilson, whose Secretary of State for Education, Anthony Crossland, outlined plans to replace the country's tripartite system of secondary education with the egalitarian comprehensive school system. The Labour-run Bexley Council agreed to this project, pushing ahead with plans to convert Chis and Sid into a comprehensive, as part of which it would be merged with the neighbouring Hurstmere in 1969. Pedley was a vocal critic of the comprehensive system on both a national and a local level. He fought the council's plans to convert the school, and was supported by a unanimous resolution passed by staff and by a Parents' Association founded in 1966. When the council nevertheless approved the plan in May 1967, Pedley resigned as headmaster in protest.