Passengers got an extra Christmas present today when the Jubilee line re-opened two days earlier than expected.
The Jubilee line was due to be closed for five days between 26 and 30 December to allow the introduction of a seventh carriage to all Jubilee line trains.
After rigorous testing of both the signalling and the newly extended seven carriage trains, a reduced passenger service was been introduced on Thursday rather than on New Year's Eve.
Conversion of the trains to seven carriages continues and a full Jubilee line service will not resume until 8 January 2006, as originally planned.
The upgrade comes six years after the opening of the Jubilee line extension, bringing extra tube services to Waterloo, Southwark and London Bridge.
Mayor of London Ken Livingstone said: "The improvements to the Jubilee line are now running ahead of schedule, which is excellent news for London Tube users.
"Although there is a limited service today, the Jubilee line is up and running a full two days early and there is now every sign that the Jubilee line upgrade is going to be a major improvement to the Tube network.
"When this work is finished, the extra carriage on every single Jubilee line train will mean we can carry an extra 6,000 passengers every morning and evening peak.
"The policy of investing in London's Public transport system, after years in which it was starved of cash, is vital to maintaining London's position as a global city."
George McInulty, London Underground's Jubilee line Service Director said: "The early introduction of the longer trains is a wonderful extra Christmas present for our passengers.
"This extra seventh carriage will be a real boost to all Jubilee line passengers, increasing capacity by nearly a fifth across the whole line, or an extra 6,000 passengers in both directions every morning and evening peak.
"In order to ensure a safe and reliable introduction of longer seven-carriage trains on the Jubilee line we had closed the line entirely.
"This is because six- and seven-carriage trains cannot be run at the same time and the trains and signalling system need to be tested prior to their introduction into passenger service.
"The extra seventh carriage on all Jubilee line trains boosts passenger capacity by 17 per cent.
"Four new trains have also been added, increasing the train fleet from 59 to 63 trains.
"While the trains are longer and carry more people, the service in place today is reduced with average gaps of up to six to eight minutes between trains.
"Some trains continue to be tested on the line.
"The replacement bus service will continue to operate today [Thursday] and tomorrow.
"Neasden station remains closed for refurbishment work."
Before the improvements, the Jubilee line capacity was approximately 33,000 people per hour in both directions when running 24 hour trains per hour.
With the introduction of seven-carriage trains and an extra four trains, LU will be introducing a new timetable in January 2006.
This will allow it to meet rising Jubilee line passenger demand and enable 39,000 passengers per hour to be carried.
• Earlier this year it was reported that the Jubilee Line extension had delivered a £78 million boost to property values around Southwark station