The line began as a part of the North London Railway but there have been many changes. The current route is the result of a series of amalgamations, closures and reopenings. There is a mixture of third rail and overhead line electric power supply. It is an important freight route and is used by the Richmond to Stratford passenger services of the London Overground. It is part of the National Rail network. Between Richmond and Gunnersbury, London Underground's District line shares tracks with London Overground services. This part is also owned and maintained by Network Rail.