Heathrow Airport is believed to have had enough power to avoid completely shutting down on Friday while a substation fire blazed two miles away.
National Grid chief John Pettigrew has since said that two other substations were fully functional and could have provided an adequate amount of power to keep the airport open.
The revelation has followed a weekend where officials and politicians scrambled to pinpoint blame for the monumental shutdown of Europe's largest airport - leading to around affected 200,000 individuals as more than 1,300 flights were cancelled.
Energy secretary Ed Miliband has since flagged his concern with the national resilience of the UK's infrastructure.
Energy secretary Ed Miliband has also since flagged his concern with the national resilience of the UK's infrastructure
PA
Heathrow chief executive Thomas Woldbye said that the unprecedented shutdown "was not created at Heathrow Airport".
He added: "It was created outside the airport and we had to deal with the consequences."
However, Pettigrew told the Financial Times: "There was no lack of capacity from the substations.
"Each substation individually can provide enough power to Heathrow."
LATEST DEVELOPMENTS:
- Heathrow Airport CEO issues apology after 'major unprecedented incident' causes thousands of cancellations: 'We are very sorry'
- Heathrow Airport: Reform’s Richard Tice blames net zero as shutdown sparks travel misery - ‘Gross negligence of the highest order’
- Heathrow Airport fire: Travel expert warns of major disruptions as thousands of passengers stranded - ‘Days to recover!’
Pettigrew explained that two extra substations are "always available for the distribution network companies and Heathrow".
He added: "Losing a substation is a unique event – but there were two others available. So that is a level of resilience."
“I can’t remember a transformer failing like this in my 30-plus years in [the] industry," the energy boss said.
A Heathrow spokesman said: "It would not have been possible for Heathrow to operate uninterrupted. Hundreds of critical systems across the airport were required to be safely powered down and then safely and systematically rebooted.
"Given Heathrow’s size and operational complexity, safely restarting operations after a disruption of this magnitude was a significant challenge."
More than 200,000 people were stranded on Friday as Europe's busiest airport shut down
PA
They added: "Lessons can and will be learned, which is why we fully support the independent investigation announced by the Government."
However, the National Grid has been burdened with accusations following the closure of the major travel hub.
Chairman of the transport select committee Ruth Cadbury has speculated whether there might be issues with the power network's capacity near the airport.
One Whitehall source claimed: "Some serious questions need to be answered by the National Grid about why the backup systems proved ineffective when the fire broke out at the substation.
"It has exposed, in a very serious way, how to bring down critical infrastructure. Ministers will be asking questions about the protection of other critical infrastructure from electrical faults."
GB News has approached National Grid for comment.
