The official name for this line is the Moorgate Line, but it is rarely referred to as this due to confusion with the Widened Lines route which goes from to . Until recently, it also served surface-level station on the London Midland Region. The Northern City Line's name is derived from the fact that it was originally a London Underground line, where it was described or managed as part of both the Metropolitan and Northern lines (sometimes as the "Highbury Branch"), although never connected to either. Built as an isolated route with a northern terminus at Finsbury Park, reconstruction connected it to the British Rail network in 1976 and began its modern service pattern. One of London's deep-level railways, the Northern City is unlike the others in being owned by Network Rail and served by commuter trains operated by Great Northern from Moorgate to Finsbury Park and onwards to Hertfordshire.