A brave new era in rail travel ground to a sudden halt yesterday just hours after train bosses unveiled their new baby.

South Central hailed a new beginning for commuters when the first of £856 million fleet of Electrostar 377 trains entered regular passenger service.

The train, complete with air conditioned carriages, sliding doors and a sophisticated computerised announcing system, left Brighton on time at 11.41am for its maiden journey to Seaford.

South Central managing director David Franks beamed with pride as he made a short speech before stepping on to the gleaming green and yellow three-coacher, saying it was "the birth of a new era in rail travel".

But just three journeys later, the train broke down, leaving South Central red-faced and early evening commuters facing their usual delays.

Passenger Russ Funnell, 24, from Pelham Road, Seaford, left Brighton on the 4.11pm Seaford service but only made it as far as Lewes.

He said: "They apologised and told us a new train they had been testing had broken down.

"They told us we had to disembark and we had to wait another 30 minutes to be bussed to Seaford."

A South Central spokeswoman admitted the company was "disappointed" about the breakdown which it put down to a technical fault affecting the power supply.

She added: "The fault has now been identified and isolated on that train, although it has temporarily been taken out of service.

"It is worth pointing out we had three other new trains running across the network today and they all appear to be fine.

"This is very disappointing and we hope to sort it out as soon as we can."

The introduction of the rolling stock was already three months late after test runs showed door-operating difficulties.

The problems have now been resolved and the company is attempting to replace its entire stock with the new trains by the end of 2004.

It was a sad end to a day which began so proudly.

The comfy seats with smart white tables, pristine windows and smoothly operating sliding doors certainly impressed passengers.

The new coaches also have a sophisticated PA system announcing stops and flashing up the next station on an electronic indicator board.

The toilets flushed properly and there were ramps available for wheelchair users.

Trainspotters and people living near the track stopped and stared as the train passed by for the first time.

Engineering student Justin Ilingworth, who was making the short journey from Brighton to Falmer said: "This is a nice way to travel. I usually drive to the university but I will certainly think of travelling by train more if they are all going to be like this."

Train drivers were also impressed with the stock.

Tony Wiggins from Polegate, who has been training the drivers on the new stock, said: "It is like going from Morris Minor to a Ferrari. All the drivers like them."

More than 1,200 train crew have had to be trained to operate the trains and platforms across the South Central network have had to be modernised to take the new units.

More Electrostar trains will be introduced along the Coastway route from Hastings to Portsmouth in the coming months and then on the main line up to London. A total of 182 trains, comprising 700 carriages costing a total of £856 million, have been ordered.

It is one of the biggest orders of train stock from a single operator.

Before the embarrassing episode, Mr Franks said: "Things like quicker journey times, greater frequency and new routes are for the future.

"Let us get the trains in service and operating efficiently first. The public wants a reliable service and that is what we have to provide.

"It is far better that we tested these trains properly before introducing them into regular service. I think we have done well to get them into use by the end of the year and hopefully we can get rid of all our slam-door stock by the end of 2004."