Heathrow Airport's  services returned to business as normal yesterday, Sunday 23 March, two days after it was forced to close when a fire at an electrical substation caused a power cut.

Europe's busiest airport had more than 1,000 flights cancelled on Friday, 21 March after the fire at the substation in Hayes, west London.

According to The Guardian, flights restarted on Saturday, 22 March, with the airport reporting more than 250,000 passengers used the airport.

Arrivals and departures continued on Sunday, although a number of flights ran with slight delays in taking off.

The paper writes: "The energy secretary, Ed Miliband, has ordered the National Energy System Operator (Neso) to investigate the power outage.

"An internal review of the airport's crisis management plans and its response to the disruption will be undertaken by the former transport secretary Ruth Kelly."

The Sunday Times reported Thomas Woldbye, Heathrow's Chief Executive, went to bed and delegated the decision to shut the airport to his deputy, Javier Echave, on Thursday night, after senior staff were split into two "gold command" groups.

One worked through the night, while the other went to bed to take over in the morning.

Heathrow officials told the newspaper that the decision was taken so Woldbye was better rested when he would take the decision to reopen the airport.

On Sunday, a Heathrow spokesperson said: "Today we will operate another full schedule of over 1,300 flights.

"We apologise for the inconvenience caused by our decision to close the airport on Friday following a significant fire at an off-site power substation.

"Yesterday, we served more than 250,000 passengers, with punctual flights and almost all passengers waiting less than five minutes for security.

"We have welcomed the government's announcement of an investigation into the cause and response to the off-airport power outage and have launched a review, to be chaired by former transport secretary Ruth Kelly, of Heathrow's response.

"While these inquiries are ongoing, our focus remains on serving our passengers."