The new 140mph trains will run between London and Kent
Guests on a test-run of the "Javelin" - Britain's fastest commuter train with a 140mph (225km/h) top speed - have been whisked from London to Kent and back.
The Hitachi train took 30 minutes to travel from St Pancras station to Ashford at an average speed of 114mph. The return journey took 29 minutes.
Southeastern will begin a limited high-speed service on the line on 29 June with a full service from 13 December.
The Japanese-built trains will reduce journey times by up to 43 minutes.
The test-run on the Channel Tunnel line passed without a hitch and was slightly quicker than the forthcoming passenger services as it did not stop at Ebbsfleet.
The services are expected to cut Ashford to London journey times from 80 minutes to 37 minutes. Ebbsfleet to London will take 17 minutes.
The trains, which have 338 seats and can carry up to 508 people, will provide the "javelin" service to take spectators from St Pancras to the 2012 Olympics site at Stratford in east London in just seven minutes.
'Value for money'
However, passengers using the Class 395 trains, which use technology from Japan's high-speed bullet trains, later this month will have to pay more for the pleasure.
Fares on the preview trains will be £26.60 from Ashford to London instead of the normal £22.20.
Existing ticket holders can pay the £4.40 supplement at any station and first-class ticket holders will be able to use the high-speed service for no extra cost.
It's a great day for passengers and a great day for UK railways
Southeastern has said the new fares "offer value for money for passengers".
Charles Horton, the train company's managing director, said the service was "great news for the people of Kent and south-east England".
The preview service will include three morning peak services from Ashford to St Pancras and three return services in the evening rush-hour. There will also be six morning services between Ebbsfleet to St Pancras and six in the evening.
The full schedule when launched in December will offer 200 services a day provided by a total of 29 trains.
Using the High Speed 1 line will mean that journeys that currently take over an hour and a half to London will be shorter.
Canterbury to London will be 59 minutes, with Folkestone 57 minutes and Ramsgate 80 minutes.
Transport Secretary Lord Adonis, who travelled on the test-run, said the high-speed trains were the "future of the railways".
"Here we have a 140mph train replacing Victorian infrastructure which can't cope with the pressures.
"It will offer the best service in to London from the Kent coast and the Medway towns. It's a great day for passengers and a great day for UK railways."
The 'Javelin' high speed train pulls out of St Pancras
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