The chief executive of National Grid has claimed that Heathrow Airport had enough power from other substations despite Friday’s shutdown.

Around 1,300 flights were affected after a fire knocked out an electricity substation in Hayes on Thursday evening. Operations were not able to resume until Friday evening.

John Pettigrew from National Grid said there were two other substations “always available for the distribution network companies and Heathrow to take power”.

In his first comments since the disruption, Mr Pettigrew told the Financial Times: “There was no lack of capacity from the substations.

“Each substation individually can provide enough power to Heathrow.”

He added: “Losing a substation is a unique event – but there were two others available.

“So that is a level of resilience.”

In response to the comments, a Heathrow Airport spokesperson said: “As the National Grid’s chief executive, John Pettigrew, noted, he has never seen a transformer failure like this in his 30 years in the industry.

“His view confirms that this was an unprecedented incident and that 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.”

Heathrow chief executive Thomas Woldbye previously said a back-up transformer failed during the power outage, meaning systems had to be closed in accordance with safety procedures so power supplies could be restructured from two remaining substations.

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But it has emerged that a report by consultancy firm Jacobs more than 10 years ago found a “key weakness” of Heathrow’s electricity supply was “main transmission line connections to the airport”.

The document, published in 2014, stated “outages could cause disruption to passenger, baggage and aircraft handling functions”, and “could require closure of areas of affected terminals or potentially the entire airport”.

In its appraisal of operational risk at the airport, Jacobs said provision of on-site generation and other measures to ensure resilient supply appeared “to be adequate” to enable Heathrow “to withstand and recover from interruptions to supply”.

The report added that the airport operated “within risk parameters that are not excessive or unusual for an airport of its type”.

Metropolitan Police counter-terrorism officers initially led the investigation but the force said the fire is not believed to be suspicious so the London Fire Brigade is now leading the probe which will focus on the electrical distribution equipment.

Heathrow is Europe’s largest airport, with more than 83.9 million passengers travelling through its terminals in 2024. Around 200,000 passengers were affected by Friday’s closure.

The chancellor has said she is “confident” 10,000 civil service jobs can be axed after numbers ballooned during the pandemic – as she seeks to cut more than £2bn from the budget.

Rachel Reeves has told Sky News she is certain the government can deliver those cuts to “back office jobs” to free up resources for “front line” services.

She is expected to unveil a raft of spending cuts during the spring statement on Wednesday – and has reportedly ruled out tax rises.

The FDA union has said the government needs to be honest about the move, first reported by The Telegraph, and the “impact it will have on public services”.

Reeves concedes cuts won’t be pain-free

Appearing on Sky’s Sunday Morning With Trevor Phillips programme, the chancellor was pushed repeatedly for a precise number of civil service jobs she wants to cut, and she eventually replied: “I’m confident that we can reduce civil service numbers by 10,000.

“And during COVID, there were big increases in the number of people that were working in the civil service.

“That was the right thing to do to respond to those challenges. But it’s not right that we just keep those numbers there forever.”

Ms Reeves said there are “a number” of civil service jobs that can be done by technology, while “efficiencies” can also be made by getting rid of quangos.

Asked what roles she expects to no longer need, she said: “It will be up for every department to set out those plans.

“But I would rather have people working on the front line in our schools and our hospitals and our police, rather than back office jobs.”

She said cuts will be made to things like travel budgets, spending on consultants, and also on communications.

She conceded that the cuts will not be pain free, but says she would rather spend money to “deliver better public services”.

Civil service departments will first have to reduce administrative budgets by 10%, which is expected to save £1.5bn a year by 2028-29.

The following year, the reduction should be 15%, the Cabinet Office will say – a saving of £2.2bn a year.

The chancellor has also said she won’t be putting up taxes on Wednesday, telling The Sun On Sunday: “This is not a budget. We’re not going to be doing tax raising.”

Ms Reeves added: “We did have to put up some taxes on businesses and the wealthiest in the country in the budget [in the autumn].

“We will not be doing that in the spring statement next week.”

The chancellor has repeatedly insisted she won’t drop her fiscal rules which preclude borrowing to fund day-to-day spending.

Civil service departments will receive instructions from the Chancellor of the Duchy of Lancaster Pat McFadden in the coming week, The Telegraph reported.

“To deliver our Plan for Change we will reshape the state so it is fit for the future. We cannot stick to business as usual,” a Cabinet Office source said.

“By cutting administrative costs we can target resources at frontline services – with more teachers in classrooms, extra hospital appointments and police back on the beat.”

The move comes after the government last week revealed welfare cuts it believes will save £5bn a year by the end of the decade.

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FDA general secretary Dave Penman said the union welcomed a move away from “crude headcount targets” but that the distinction between the back office and frontline is “artificial”.

“Elected governments are free to decide the size of the civil service they want, but cuts of this scale and speed will inevitably have an impact on what the civil service will be able to deliver for ministers and the country…

“The budgets being cut will, for many departments, involve the majority of their staff and the £1.5bn savings mentioned equates to nearly 10% of the salary bill for the entire civil service.”

Ministers need to set out what areas of work they are prepared to stop as part of spending plans, he said.

“The idea that cuts of this scale can be delivered by cutting HR and comms teams is for the birds. This plan will require ministers to be honest with the public and their civil servants about the impact this will have on public services.”

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Mike Clancy, general secretary of the Prospect union, warned that “a cheaper civil service is not the same as a better civil service”.

“Prospect has consistently warned government against adopting arbitrary targets for civil service headcount cuts which are more about saving money than about genuine civil service reform.

“The government say they will not fall into this trap again. But this will require a proper assessment of what the civil service will and won’t do in future.”

An electrical substation fire and an entire airport shut down – with over 1,000 flights cancelled, others rerouted worldwide, and 200,000 passengers affected by the disruption.

The Heathrow closure on Friday really highlights the ‘critical’ part of critical national infrastructure (CNI) – the systems and facilities that are essential for society to function.

At best it’s an embarrassment. At worst, it points to serious vulnerabilities across the country that could be exploited by bad actors.

Heathrow first.

Heathrow needs a lot of power, the equivalent of a small town, and the bulk of this is supplied by a dedicated connection at the North Hyde substation – reflecting Heathrow’s critical status.

But that also appears to be the problem – because Heathrow requires so much power, having a second dedicated connection would likely be prohibitively expensive, especially for the low probability scenario of such a catastrophic fire. This is the first time this has happened in decades, after all.

“Fires like this are not common at all,” said Dr Robin Preece, a reader in future power systems at the University of Manchester. “If it just broke down without catching fire… you might never have noticed anything as we have sufficient alternative routes for the electricity to follow.”

But uncommon doesn’t mean impossible – and when infrastructure is critical, it’s supposed to be protected.

MI5 in charge of critical infrastructure protection

The organisation ultimately responsible is MI5, through the National Protective Security Authority. This lists 13 national infrastructure sectors, from chemicals to nuclear, emergency services to food, space to water.

It’s a lot to look after – this map shows just some of the sites that would be considered CNI. Airports and power stations. Or the tubes that supply us with energy (gas and fuel pipelines) and internet (undersea cables).

Many of those risks are collected in the National Risk Register. This plots the likelihood and the impact of a risk.

Measuring risk chances and impact

So an accidental fire or explosion at an onshore fuel pipeline is estimated to have less than a 0.2% chance of happening in the next two years but would have only a “moderate” impact, defined as between 41-200 casualties and/or hundreds of millions of pounds in economic losses.

A civil nuclear accident has a similar probability but would have a “catastrophic” impact, defined as the loss of more than 1,000 lives and/or an economic cost of tens of billions of pounds. Pandemics also meet the catastrophic impact threshold.

A regional failure of the electricity network, one due perhaps to “a specific power substation”, is listed as having a 1% to 5% chance of happening every two years, and a moderate impact. But this is what happened to Heathrow – and the impact doesn’t appear moderate at all.

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Catalogue of vulnerabilities

The National Risk Register is sensible planning but it’s also a catalogue of vulnerabilities.

Accidents do happen, but so do attacks. It can be hard to tell the difference – and that’s the point of what are known as “grey zone” attacks.

For example, undersea cables keep unfortunately being cut, whether in the Baltic Sea or the waters around Taiwan.

Taiwan has accused China of doing this deliberately. China responded by saying that damage to undersea cables is a “common maritime accident”.

“Malicious actors see opportunities and vulnerabilities”, Marco Wyss, Professor of International History and Security at Lancaster University, told Sky News.

“And if you showcase vulnerabilities to such an extent as today, even if it wasn’t a malicious actor, it can give them some ideas.”

Additional reporting by Sophia Massam, junior digital investigations journalist