Around 4,000 years ago, just 5 miles north of what is now the Norfolk town of Thetford, our Neolithic ancestors began what may have been the largest early industrial process in these British Isles. This is the site that the Anglo-Saxons called ‘Grimes Graves’ and it contains nearly 400 mine-shafts built to extract high-quality flints, which could be chipped to produce sharp cutting edges. Using nothing but tools of bone and wood, and presumably the flints themselves, these ancient people excavated to a depth of up to 12 metres to reach the buried flints. It has been calculated that the miners needed to remove 1,000 tonnes of waste to produce 8 tonnes of flint. The site covers nearly 40 hectares and the whole project is astonishing.

Whilst more advanced technologies had developed elsewhere – for instance in China – our ancestors' task was anything but easy. They needed timbers to shore up their excavations and ladders to get down into them; lighting was required in the deeper pits and they needed tools, which they made from deer antlers, so they had to manage the local herds of red deer. A separate and skilled industry was required to work the extracted flints and to market and distribute them. The flints were used as axe-heads, as agricultural implements, as arrow-heads, and no doubt there were countless other applications that we have lost track of. The Grimes Graves operation underpinned the foundations of a new sort of society.