This is the end of live updates on the power cut across large areas of England and Wales, which affected nearly one million people.

Homes and transport networks were hit, with thousands of passengers finding themselves stranded at major railway stations in London.

BBC News will be updated throughout the night and you can read the latest story here.

National Grid has told the energy regulator Ofgem that power has been restored to the system - but now it faces a simple question: what went wrong?

"In any incident the priority is to get power restored to customers as quickly as possible," Ofgem said in a statement.

"However, Ofgem understands the frustration this power cut has caused consumers. Ofgem has asked for an urgent detailed report from National Grid so we can understand what went wrong and decide what further steps need to be taken. This could include enforcement action."

National Rail has just confirmed what everyone stranded at Kings Cross already knows - there will be no end to the disruption tonight... and there's likely to be more tomorrow.

Earlier, LNER said it had managed to start running services into London again after moving a failed unit from the line. Bad news though - it has failed again...

There have been trains running to Stevenage and Peterborough but no further up the east coast mainline as yet.

Trains on the way to London might not be able to take passengers back as drivers might have worked too many hours, LNER staff at the station have said.

Image source, PA Wire

Bob Dale
BBC Live reporter

Some people have been able to get home, or to the events they were heading for this evening.

Others haven't been so lucky.

Professor Keith Bell, expert in electronic and electrical engineering at the University of Strathclyde said today's power cut was similar to an outage 11 years ago, when two power stations failed.

"It seems to have been a very similar event to one in Britain in May 2008," he said.

"However, this time we were kind of unlucky in that it was a deeper drop in frequency so more demand was tripped, and it happened during rush hour."

A lot has changed in the Britain since 2008, not least the layout of our website.

London North Eastern Railway has said that services are now running into London after a broken train was moved. However, it said that it would "take some time to clear the backlog".

National Rail Enquiries has said that Great Northern and Thameslink passengers affected by the power outage will be reimbursed the cost of a taxi home.

However, when one Twitter user asked if they would be reimbursed for a taxi from London to Peterborough, National Rail Enquiries advised that he "speak to the train operator used to purchase tickets".

Some passengers have been forced to embark on epic journeys as they attempt to find a way home through the cancellations.

Francesca, we salute your effort.

Natasha Winters was among those to be evacuated from a Thameslink train stuck outside King's Cross.

She said: "It was a bit scary, a bit freaky, to be honest. We could see right down the tunnel [towards St Pancras]."

The civil servant, 47, said there was a "good atmosphere" on the train, which had been stuck in a tunnel without lighting for about two hours.

"We were just sat around chatting and having a laugh. I met some really nice people, they were just random strangers.

"People were having fun and joking about it, talking about what we were supposed to be doing. Someone was meant to be getting the Eurostar to Brussels. They had completely missed that."

Ben Ando
BBC News

The enormous impact of this power failure is likely to lead to questions being asked about the strength and robustness of the system.

The BBC understands that two power supply plants – one a traditional gas and steam fired power station in Cambridgeshire, the other a huge wind turbine farm in the North Sea – failed at around 16:00 BST. The National Grid described it as an “unexpected, and unusual event.”

An additional factor may have been capacity problems at Britain’s largest single power station in Yorkshire.

The sudden drop in available power caused protective measures to kick in that immediately cut electricity supply to a section of the national grid network. This in turn led to power cuts affecting around half a million householders across England, as well as causing electric trains to grind to a halt and traffic lights to go dark.

By 18:30 the problems were fixed and the system was described as operating normally by the National Grid. But the knock-on effect is likely to be felt for several hours to come.

Gail Jackson was stuck on a train from Grantham in Lincolnshire to London King's Cross for more than two hours.

Staff on the train had told her that "people were trying to get off" without permission. She added: "It was so hot."

The train was stopped at Welwyn Garden City, before returning to Stevenage, where passengers were told to leave the train. She said they were advised to abandon hopes of travelling to London.

Ms Jackson, chief executive of the charity Community Lincs, said fellow passengers had pre-booked theatre tickets, and one family had been due to catch a Eurostar train to Paris for a holiday.

She said passengers were "being quite lovely and helpful to each other", sharing phone chargers and information.

"The on-board staff were lovely and were going around with water, but unfortunately they weren't getting any information."

Ms Jackson, 48, was able to board a later train to London, which was at a standstill near Stevenage as she spoke to the BBC.

Rail users are now being advised that they will not be able to travel from either King's Cross or St Pancras stations for the rest of the evening.

As a result of the disruption National Rail has said services will also be affected on Saturday.

UK Power Networks advises you to get in contact.

BBC journalist Vikki Irwin was with her mother at Ipswich Hospital when the power cut hit at about 17:00 BST.

Her mum was on a hydraulic lift being moved up to a scanner when the outage happened.

“My mum was being lifted up and was near the top when all these sirens went off in the hospital and the lift stopped,” she said.

Her mother, a cancer patient, had to be manually helped back into a wheelchair.

The lifts in the hospital were also out of order, resulting in patients having to be carried down the stairs by hospital staff.

Parts of the hospital were in darkness, however the A&E department was not affected.

Bob Dale
BBC Live reporter

Journalist and BBC Front Row presenter Stig Abell is one of those caught up in tonight's disruption.

Bob Dale
BBC Live reporter

This commuter says that, while the lights are out, Clapham Junction seems to still be operational.