For many years until 1961, the night routes were numbered from around 280 to 299. But the imminent withdrawal of trolleybuses meant that numbers between 1 and 299 were in short supply. The 280+ route numbers were freed by giving night bus routes a prefix N for the first time. For example, while route 9 travels from Aldwych to Hammersmith, route N9 continues a further 16 miles (26 km) from Hammersmith to Heathrow Terminal 5. There are also 24-hour routes, which run throughout the day and night. These do not have distinguishing numbers. Some of these only run at night during weekends, whereas others run throughout the week. Heritage routes Following the withdrawal of rear-entrance double-deck AEC Routemaster from all regular service routes in 2005, a small fleet was retained to operate on heritage routes. As the AEC Routemaster buses were not accessible to passengers in wheelchairs and other mobility impaired passengers, the heritage route was operated as a short-working of a regular service route bearing the same route number, thus ensuring that passengers unable to board the heritage buses are offered equivalent alternative transport arrangements. Initially running on route 9 and route 15, Route 9H was withdrawn on 26 July 2014. In 2019, the remaining heritage route 15 was cut back to a seasonal service, running on weekends and bank holidays through the summer. In 2021, TfL announced that the heritage route would not return following the COVID-19 pandemic. In 2022, a private operator started operating 'Route A', a tourist focused heritage route between Piccadilly Circus and London Waterloo using AEC Routemaster buses. Unlike previous heritage routes, a higher fare is charged. Tour buses A common sight in central London are tour buses, the majority being open-top buses. These are double-decker buses with a fully or partially open upper deck, which provide tourist services with either live or recorded commentary. Most of these services allow passengers to embark and disembark at any of the company's stops, continuing their journey on a later bus. There are several competing operators of such services which do not form part of the London Buses network and do not issue or accept London Buses tickets, although at least one paints its buses in the same red as London's local buses. Other tours use coaches and generally need to be booked in advance through travel agents. Long distance coaches Long-distance coaches link London with the