A report into a fire that resulted in Heathrow Airport shutting down for nearly a day has been released - what are the key findings?

An inquiry has found that an electrical substation fire that shut down Heathrow Airport in March was caused by a preventable technical fault identified almost seven years earlier.

A fire that shut Heathrow airport in March, stranding thousands of passengers, was caused by National Grid's failure to maintain an electricity substation, an official report said on Wednesday, prompting the energy watchdog to open a probe.