Around 200,000 passengers were disrupted after the airport was closed to all flights on Friday until around 6pm after the fire.
A fire at an electrical substation that closed Heathrow Airport and disrupted 200,000 passengers is no longer considered a potential crime by the Metropolitan Police. The fire's cause is still under investigation by National Grid, London Fire Brigade, and Southern Electricity Network, and Heathrow's chief executive will be questioned by MPs.