The red double-decker is one of London’s most famous symbols. There are a wide variety of theories as to why red was chosen. At very start of the 20th Century, when the majority of vehicles were still drawn by horses, buses came in a range of colours. Red only rose to popularity when, in 1907, the London General Omnibus Company (LGOC) rouged up its fleet to distinguish itself from the competition. LGOC soon came to dominate the early PCV market; it chose to extend the colour to most of the capital’s buses.

Source: Backhouse Jones