The surprising reason every Tube line has its own colour

Millions of people use the London Underground every year, but few stop to wonder why every Tube line has its own distinctive colour or how those famous shades were chosen.

From making journeys easier to navigating one of the world’s busiest transport networks, the coloured map has become a global design icon. The story behind it reveals how practicality, clever design and a little history transformed the way London travels.