Britain’s substations are bursting into flames. The answer might be more worrying than the Russians

It started late on the evening of March 20 when a bang broke the reassuring hum at the North Hyde electricity substation near Heathrow Airport. One of the plant’s two “supergrid” transformers – giant pieces of equipment that step down high voltage power so it can be used by nearby homes and businesses – had exploded and set itself on fire.