In 1959–1960 Circle line trains were increased to 6 cars, the same length as those operating on the Hammersmith & City line, and the stock of the two lines was integrated with maintenance concentrated at Hammersmith depot, allowing Neasden depot to concentrate on the new A Stock. Aluminium C Stock trains, with public address systems and originally unpainted, replaced these trains from 1970. One person operation of the trains was proposed in 1972 but, due to conflict with the trade unions, was not introduced until 1984. In 2003, the infrastructure of the Circle line was partly privatised in a public–private partnership, managed by the Metronet consortium. Metronet went into administration in 2007 and the local government body Transport for London took over responsibilities.