Power went off about 18:26 British Summer Time.
Even before the blackout the UK press was anticipating a UK equivalent of the 2003 U.S.-Canada Blackout, which occurred two weeks earlier (August 14) and affected about 100 times more people. For example, on August 15, The Daily Express had reported that the National Grid might not be able to cope with predicted power surges in the winter of 2004.
On the day of the blackout London Mayor Ken Livingstone declared the situation a "catastrophic failure" and "the normal British disease of underinvestment and not keeping your plant up to date". The press followed this lead. The power transmission company National Grid responded that, as they had invested £3000 million in the last 10 years, the system certainly could not be described as old and decrepit.
Headlines such as "Power cut cripples London" (CNN) concealed the fact that over 90% of London's population was unaffected.
Later it became clear to the press that the blackout might not be directly attributable to underinvestment, but this was still the main thrust of the stories: e.g. The Independent, 30 August: "Just admit it, Mr Urwin. National Grid needs to invest more".
On 8 September the London Evening Standard ran a story "Blackout report will take weeks" [1]. On 10 September National Grid published a 43-page report describing the causes of the blackout (and made it available on the internet [1]). The national BBC TV evening news did not cover this.
In mid October an anonymous National Grid engineer spoke to the BBC. It emerged that there may have been a maintenance problem not covered in National Grid's report (see below).
Initial reports were that there appeared to be a problem with a cable feed from the national grid in the Wimbledon area of south London. A spokesman for National Grid said it was "an unusual occurrence", but "not even vaguely on the scale of what happened in the U.S.",
adding that there was a fault in the 275 kV system. Later, Chief Operating Officer Mark Fairbairn said the problem was caused by the extremely rare coincidence of two faults happening only seven seconds apart.
Later National Grid's report revealed that the second fault, and the ultimate cause of the blackout, was the fitting of a wrongly rated part in a backup system - similar to fitting a 1 amp fuse instead of a 5 amp fuse. The first fault was a problem with a transformer. The impression was given that this fault was in a sense routine - about 13 such faults happen in a year. Normally it would be possible to switch the transformer out of the system and continue with power uninterrupted, but in this case the switch over exposed the second problem.
On 17 October it emerged that the transformer fault was due to an oil leak, spotted some weeks before the blackout. The oil had been topped up but the leak had not been cured. National Grid's Director Of Transmission admitted to a "small backlog" of maintenance checks. On 21 October it became clear that the leak had been known of since March. National Grid had started a regular programme of topping-up until the transformer could conveniently be serviced. Evidently this was ultimately not enough to keep up with the leak; "it got bigger" said a spokesman.
National Grid's parent company, National Grid Transco operates the U.S. business Niagara Mohawk, which was among those involved in the earlier US-Canada blackout.
The London fire brigade took around 400 calls and made 100 rescues of people stuck in lifts. All main rail services were at a standstill in south London and the south-east. Sixty percent of the London Underground was affected (London Underground had shut down the last of their independent generators in favour of using Grid supplies in 2002) and people were stuck underground. 270 sets of traffic lights were hit. To relieve the transport problems, busses took passengers with train and Tube tickets. Thousands of people took to the rain-soaked streets. Pubs filled up with people sitting out the delays.
Power came back on after 34 minutes at 19:00 BST, but is reported to have taken about two hours to be restored fully in some areas.Immediate impact
Media coverage
Causes
Effects
Restoration of Service