Although sat nav devices are associated with the digital age, they had a remarkable precedent in the Plus Fours Routefinder, created in 1920. This device took the form of a UK road map on a small scroll, mounted on a wristband; by rotating rollers, the map on the scroll could be turned, enabling a driver to navigate the route. A number of different route scrolls were included, each of which included helpful directions, mileage and a ‘Stop’ instruction, informing the driver when the journey had been completed.

Perhaps the Routefinder was too far ahead of its time (or there simply weren’t enough car drivers in the 1920s to warrant its invention). It was never a commercial success.