When 19th-century engineers decided their new-fangled locomotives could be driven underground beneath London's crowded streets, they began a tradition for technological innovation that the capital's transport system has never lost. Today the cutting edge has moved from steam to cyber, but the driving force is the same as it was for the Victorians – how can more people be moved more quickly and efficiently through the capital's jumbled, crowded streets? At the heart of this is no nimble tech startup, but the capital's transport authority, Transport for London, which vaunts its record as an innovator in the field with some justice, according to the experts. "It's a tradition that goes right back into the beginnings of London Transport," said Professor Stephen Glaister of the RAC Foundation. "One reason they are so important is simply that they are so big. For example, what London buses does tends to influence what the manufacturers do ahead of anyone else." That scale, he says, has helped the city take a lead in everything from adopting diesel-electric hybrid buses, to revolutionising ticketing systems, he said, pointing to integrated travelcards in the 1980s, through to the Oyster card in 2003 and now contactless payments. "With London being so big and so dense, the economics of public transport have been much more favourable. It's worth spending money on new technology."