LONDON, July 2, 2025 (BSS/AFP) - A fire at an electrical substation that forced a shutdown at London's Heathrow Airport in March was likely caused by moisture entering electrical components, a problem first flagged in 2018, a report said Wednesday.

Water entering a transformer and causing a short circuit "most likely" started the fire, according to the National Energy System Operator (NESO) report, adding that elevated moisture readings were detected in July 2018 but "mitigating actions appropriate to its severity were not implemented".