In 2019, older bigots and veteran xenophobes still recalled with pride the successful campaign Boston and the area of Lincolnshire around it waged in the 1960s against the rodent coypus, foreigners from somewhere foreign with tomato-red teeth, who had been introduced to Britain in the 1920s as a fur crop called nutria. Once these shy, intelligent South American beasts got wind of their fate, they began to escape from the 50 or so “farms” that had imported them, head for wetlands, breed prolifically, guzzle crops (wheat, beetroot, turnip) and destabilise fen dykes by burrowing into their banks.