Many services commence from or operate via Trafalgar Square and are extensions or variations of daytime routes and hence derive their number from these; for example, route N73 Oxford Circus to Walthamstow follows that of route 73 as far as Stoke Newington, before continuing further north.
The first night bus was introduced in 1913. A few more services were introduced over the following decades, before all ceased during World War II. Services resumed after the war, increasing as trams and trolleybuses were replaced in the late 1950s and 1960s. In April 1984, the number of routes was increased from 21 to 32. At this point the peak service required 80 buses, by August 2013 this had grown to 890.
Originally the night bus network had its own fare structure, but with the introduction of the Oyster card in 2003, was incorporated into the Transport for London fare structure. Up until the mid-2000s, all routes had N prefixes. However, as some routes merely mirrored their day time equivalents, the N prefixes were dropped and these routes became 24-hour services; for example, route N14 was no longer differentiated from route 14.
Services are operated by private operators under contract to London Buses. The Night Bus contracts are often bundled with that of the equivalent daytime route and awarded for a five-year period, with an optional two-year extension based on performance standards being met. Some however are tendered individually.
With some London Underground lines operating a 24-hour service from August 2016 on weekends, a further eight routes commenced 24 hour operation on Friday and Saturday nights. Further changes are expected as the Night Tube network is expanded.