Published: 11:00 PM August 9, 2019 Updated: 6:32 PM September 17, 2020

People walking in complete darkness at Clapham Junction station in London during a power cut, which has caused apocalyptic rush-hour scenes across England and Wales. Photograph: Yui Mok/PA Wire. - Credit: PA

The power cuts which affected almost a million people in England and Wales on Friday evening are a 'sign of things to come', a union leader has claimed.

People waiting for trains at King's Cross station, London, after all services in and out of the station were suspended on Friday when a power cut caused major disruption across the country. Photograph: Abbianca Makoni/PA Wire.

Traffic lights stopped working, Newcastle Airport fell into darkness and Ipswich Airport was affected by the power loss incident.

Major disruption also hit the country's railways during the busy Friday night commute.

Frustrated travellers continued to experience disruption to services at London's Kings Cross station on Saturday.

Speaking to the BBC Radio 4 Today programme on Saturday morning, Duncan Burt, operations director at National Grid, said the power cut was an "incredibly rare event".

Chancellor Sajid Javid at the National Grid Training Centre near Newark hours before a power cut. Photograph: Joe Giddens/PA Wire

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He explained that the two power stations disconnected from the grid "near simultaneously".

Burt said: "What happened then is our normal automatic response mechanisms came in to help manage the event, but the loss of power was so significant that it fell back to a set of secondary back-up systems which resulted in a proportion of electrical demand across the country being disconnected for a short period to help keep the rest of the system safe."

He added: "Those events happened very, very quickly, in a matter of a few seconds, maybe a couple of minutes maximum.

"That sequence of events is entirely automatic, we think that worked well, we think the safety protection systems across the industry on generators and on the network work well to secure and keep the grid safe."

But Manuel Cortes, general secretary of the Transport Salaried Staffs Association, said it "foretaste of things to come" as the likeliness of a no-deal Brexit increases.

He said: "We urgently need answers from the government over this fiasco. Having our rail network brought to a standstill in this way is totally unacceptable.

"We've seen thousands of passengers stranded, unable to board trains and a number of cancellations; others have been taken off trains and onto the tracks. We need to know why this occurred and the lessons to be learned.

"As we face the growing prospect of a No Deal Brexit it's reasonable to wonder if this is a foretaste of things to come. Along with an economy sliding towards recession and expected food shortages we now seem to be a country where blackouts happen without warning, travel grinds to a halt, traffic lights stop working and - terrifyingly - hospitals are left without power.

"Boris Johnson can't remain silent over this - he must quickly provide answers and illumination."

The power cuts hit just hours after chancellor Sajid Javid paid a visit to the National Grid.