Heathrow – the UK’s and Europe’s busiest airport – closed for hours until about 6pm on Friday while thousands of homes were left without power in the area. Counterterrorism detectives confirmed last week the matter is no longer ‘a potentially criminal matter’ after they were called in to investigate the fire.

The official said he had raised concerns about Heathrow’s electricity supply days before a power outage forced it to shut down. Heathrow disputed the relevance of the official’s comments.

The boss of Heathrow Airport has apologised to the over 200,000 passengers whose journeys were disrupted by its closure last month following a fire. Thomas Woldbye offered his "deepest regrets" adding that the "situation was unprecedented". Speaking to MPs, he said he recognised "the considerable inconvenience and concern it caused".