A short drive from London, the town of Potters Bar is separated from the village of South Mimms by 85 acres of rolling farmland segmented by a scribble of hedgerows. In one of the fields, a lone oak serves as a rest stop along a public footpath. Lately, the tree has become a site of protest, too. A poster tied to its trunk reads: “NO TO DATA CENTRE.”In September 2024, a property developer applied for permission to build an industrial-scale data center—one of the largest in Europe—on the farmland...