There are now two companies, called Acorn and Mosaic, that have gone further. They use census data, retailers’ own information, and other sources (all those times you forget to tick the “don’t pass on my information” box) to split Britain’s 1.9 million postcodes into about 60 different social groupings. All of these categories are given names, some of which are innocuous, such as “summer playgrounds” or “sprawling subtopia”. Others are a fairly stark assessment of the householders’ prospects: “white van culture” and “multi-ethnic crowded flats”. These data are then sold back to retailers to help them chase some customers – and avoid others.