UK electricity supplier National Grid Transco (NGT) said that without the £3.5bn invested in its IT systems over the last 13 years, the power cut which caused chaos in London last night could have been much worse.
Faults at sub-stations in Wimbledon and Hurst plunged parts of rush-hour London and the South East into darkness.
The power loss stranded 250,000 commuters packed on the London Underground and train services from south London into Kent and Sussex. Police said 270 traffic lights across the capital were knocked out of action.
But a spokesman for NGT told vnunet.com that its IT systems, based at the control centre in Berkshire, were able to detect the fault and alert engineers.
"The power cut was caused by problems at two separate sub-stations, which is quite unusual," he said.
"Our systems alerted us, and allowed us to get guys down there and start to restore power within half an hour."
NGT has spent £3.5bn updating its IT systems since it was privatised in 1990.
If a disruption in the transmission of electricity across its 4,500 miles of overhead and 400 miles of underground high-voltage cables is identified, the system sets off an alarm in the Berkshire control centre.
The systems then automatically attempt to restore power. If this is not possible, another alarm is raised, and engineers are sent out.
The IT systems are also responsible for re-routing power where necessary.
Last night's outage infuriated politicians, who were left fuming that any sort of power cut could affect the nation's capital.
"The lives of every person, family and business are affected in a devastating manner by interruptions to electricity supply," said Tim Yeo, the shadow trade and industry secretary, in a statement.
And Yeo was joined by the Confederation of British Industry (CBI) in his call for an investigation into how Londoners were left without electricity.
"Clearly this has caused a great deal of frustration," said Mary Rance, director of CBI London.
"What is needed now is a calm assessment of what went wrong in this unusual set of circumstances. Then we can judge if action is needed to make sure it doesn't happen again."
The CBI said it was too early to calculate the cost of the power failure to business.
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