In 1948, the National Health Service Act 1946 made it a requirement for ambulances to be available for anyone who needed them. The present-day London Ambulance Service was formed in 1965 by the amalgamation of nine existing services in the new county of Greater London, and in 1974, after a reorganisation of the NHS, the LAS was transferred from the control of local government to the South West Thames Regional Health Authority. On 1 April 1996, the LAS left the control of the South West Thames Regional Health Authority and became an NHS trust.