National Grid, the electricity system operator in the country, said the outage on Friday was caused by issues with two power generators but the problem was now resolved, the BBC reported.
According to Professor Tim Green, co-director of the Energy Futures Laboratory, Imperial College London, the first generator to disconnect on Friday was a gas-fired plant at Little Barford in Bedfordshire at 4.58pm.
A statement by National Grid on Friday night said the issue had been resolved, though train services across the country were widely disrupted, with carriages being stranded in some areas.
Andrew Adonis, a former chairman of Britain's National Infrastructure Commission, said National Grid had "some big questions to answer" about how a relatively brief power cut had caused nationwide mayhem on the railways. Frustrated travellers continued to experience disruption to services at London's Kings Cross station on Saturday.
The committee will look at whether National Grid, which manages the electricity supply system, stuck to its processes and procedures and if these were fit-for-purpose. He said it was unclear whether the two near-simultaneous outages were connected or it was a coincidence. Two minutes later Hornsea Offshore wind farm seems to have disconnected.
Burt said National Grid is due to provide a "a detailed technical report" to Ofgem, which has already urgently demanded information as to what went wrong.
A spokeswoman for Northern Powergrid, which serves Yorkshire and the North East, said 110,000 of its customers lost power, while at least 26,000 people were without power in the North West of England, Electricity North West said.
Other train services in and out of London - including Thameslink, Southern and the Gatwick Express - faced delays and cancellations because of the disruption.
Newcastle Airport was also plunged into darkness during the major power cut.
The Department for Transport confirmed they were working with Network Rail to reduce disruption.
"We believe this is due to a failure on National Grid's network, which is affecting our customers". Western Power Distribution said 90 percent of their affected customers had their power restored by 5:45 p.m., and work was continuing to restore power for everyone.