The growing death toll during this heatwave is horrifying. Children setting out to cool off are not coming home. Families expecting an ordinary summer day are instead being left with unbearable grief that will haunt them forever. Rivers, lakes and reservoirs may look inviting in soaring temperatures, but open water can kill frighteningly fast. Hidden currents, freezing temperatures, and cold-water shock do not care how hot the weather feels. Warnings must be taken seriously. But Britain also