London in 1900, the centre of empire. The Central Line underground railway is being constructed with picks and shovels. The vast majority of London’s traffic is horse drawn, but it clutters the streets nonetheless, leaving a layer of manure that – so some believe – will eventually lie feet deep and overwhelm the capital. Getting across Piccadilly Circus or Parliament Square can be a laborious and dangerous business. What research has been done shows that the average journey time, door to door, across central London is just 12 miles per hour (mph).1 It wouldn’t be quicker to walk, but it feels frustratingly slow.