The core operation of the West London line is the metro/commuter rail operated by London Overground. Four trains per hour run between Clapham Junction and Willesden Junction, with most trains continuing on the North London line to and from Stratford. It forms the western section of the Overground's orbital rail route which was completed in December 2012 when the East London line was extended to Clapham Junction via the South London line, linking it to the West London line .
