Londoners are facing historic levels of subsidence risk after five successive heatwaves dried out the clay soil on which much of the British capital is built.Insurance claims tied to subsidence – a phenomenon associated with bouts of hot, dry weather that shrink the soil and destabilise the foundations on which buildings stand – hit a record last quarter, according to data provided by the Association of British Insurers (ABI). On average, households claimed £20,000 (US$27,200) for the risk,...