“Sometimes it’s better to light a flamethrower than curse the darkness,” wrote the late Discworld author in Men at Arms. The Pratchett estate has authorised the use of the name, tweeting its own Pratchett quote in support of Monroe’s campaign. A man who could afford fifty dollars had a pair of boots that’d still be keeping his feet dry in ten years’ time, while a poor man who could only afford cheap boots would have spent a hundred dollars on boots in the same time and would still have wet feet.” But the thing was that good boots lasted for years and years. Those were the kind of boots Vimes always bought, and wore until the soles were so thin that he could tell where he was in Ankh-Morpork on a foggy night by the feel of the cobbles. But an affordable pair of boots, which were sort of okay for a season or two and then leaked like hell when the cardboard gave out, cost about ten dollars. A really good pair of leather boots cost fifty dollars. He earned thirty-eight dollars a month plus allowances. “The reason that the rich were so rich, Vimes reasoned, was because they managed to spend less money,” wrote Pratchett. She was soon working with economists, charities and analysts to compile her own index.

She laid out how the prices of “value” product ranges in supermarkets had soared over the last decade – rice in her local supermarket had increased in price from 45p for a kilogram bag last year, to £1 for 500g, a 344% increase – and how the number of value products has shrunk. Monroe was prompted to create her index after inflation jumped to 5.4% last week, and she found herself “infuriate” that the index (the consumer price index or CPI) used for this calculation “grossly underestimates the real cost of inflation as it happens to people with the least”. The author’s daughter, writer Rhianna Pratchett, said her father would have been proud to see his work used in this way by the anti-poverty campaigner. Terry Pratchett’s estate has authorised Jack Monroe to use the “Vimes Boots Index” as the name of her new price index, which is intended to document the “insidiously creeping prices” of basic food products.

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