But the incident was immediately pounced upon by passenger groups and transport campaigners as an example of the poor state of London's underground railway system.
The problem was traced to the 91-year-old Lots Road power station in Fulham, which provides nearly all the electricity for the system of 11 lines and 248 stations. An estimated 20,000 people were trapped for up to two hours after the failure of a control valve on one of the main gas boilers at the power station.
London Transport said that eventually all the trapped trains were brought to stations where people were able to get off onto platforms.
This is the third major electrical failure in the past three years. In April a power cut, which officials then called the "worst ever", hit the Underground, causing chaos for Easter tourists and sports fans after a fire in a cable near Earls Court station.
And on 23 November 1993, the Central Line stopped running and it took a week to find the fault which was traced to a cable in the roof of Lots Road.
While London Transport says that these immediate problems are not related to the years of under-investment, which are apparent to all the 2.7 million daily users of the system, it is very concerned that its spending plans will be an easy target in next week's Budget.
With road-building already being cut, and the subsidies paid to private rail companies protected by government commitments, the pounds 400m given to London Transport last year is set to be drastically reduced, despite warnings by business leaders and passenger groups.
Last month, a leaked report from London Transport revealed that services would have to be cut and speed restrictions implemented because of the poor state of many parts of the system. The report warned of widespread problems with water penetration which could cause electrical failures such as the one on Wednesday night.
It also suggested that one station, Ladbroke Grove, in west London, was in danger of totally collapsing on its own foundations, and that falling masonry could hit passengers.
Capital, the pro-public transport group, said that part of the problem is low morale at the Lots Road power station. The plant is likely to be closed down after the supply of power to the London Underground is privatised.
Four consortia are competing to supply electricity to the system in a 30-year contract being offered under the Government's Private Finance Initiative. The contract will involve the operation, maintenance, financing and renewal of the Tube's high-voltage power supply.
London Transport said that it expected to be able to award the contract to the winning consortia next spring.Reuse content