Facts about London buses

Why are the buses red?
Before 1907, buses were painted in different colours to signify their route. Due to fierce competition between bus companies, London General Omnibus Company (LGOC) – which became the biggest bus operator in the capital – painted their fleet of buses red in order to stand out from the competition. After encouragement from the Metropolitan Police they also introduced numbers on the buses to signify different routes.

Two iconic Routemasters are still in use
The Routemaster bus is symbolic of London but this couldn’t save them from being withdrawn from service on 9th December 2005. They were replaced with easy access low-floor buses. However two Routemasters are still in use today on heritage routes. These are Route 9 from Kensington High Street to Aldwych and Route 15 from Trafalgar Square to Tower Hill.

A competition found the new London bus design
In his 2008 election campaign, Boris Johnson vowed to bring the Routemaster back to London. The design of the bus was subject to a competition, with international design companies submitting entries. The winning designs were chosen, altered slightly, and in 2010 the final design was unveiled.

The Knight Bus was commissioned in 1865
Well, at least that's what J.K. Rowling would have you believe. The bus seen in the film Harry Potter and the Prisoner of Azkaban was constructed using three RT-Class AEC Regent III buses. It is summoned by sticking your wand in the air, as a muggle might hail a taxi. The service is generally used by wizards who are underage or infirm. Hot chocolate is available for the sum of thirteen sickles and there are many beds on which to rest a wizard's head.

The bus in Cars 2 is named Topper Deckington III
The iconic Routemaster bus makes a cameo appearance in the Pixar film Cars 2. Named Topper Deckington III, his route around Killswitch goes via Carford Street, Shiftly Road and Petroldilly Circus. One bus features an advert for ‘Calahan’s Gastropub & Knittery’ which is a reference to the film's lighting director Sharon Calahan.

Source: http://www.gizmodo.co.uk/2014/01/18-things-you-didnt-know-about-london-buses/