The operator believes the new rolloing stock will deliver more comfortable, quieter, greener and reliable journeys along the East Coast Main Line.

National Express East Coast operates 13 diesel high speed trains in total and all will receive a complete interior makeover by 2009.

The refurbishment work is being carried out by Wabtec Rail in Doncaster.

Richard McClean, National Express East Coast's production director, said: "We are making good progress with the project to transform the popular 125 diesel trains.

"They have given fantastic service and in their new, much improved condition, will continue to set high standards for years to come."

The new–look interiors feature brighter and more spacious interiors.

Design features include new, softer contoured seats with improved back support, and fold-up armrests for easier access; new luggage racks offering more storage space; new tables, carpets and lighting; new toilets and vanity units; laminated glass windows; and refurbished vestibules.

All National Express East Coast trains are fitted with wireless internet, which became free of charge to passengers in both first and standard class from day one of its franchise on December 9, 2007.

For the longer term, the Department for Transport (DfT) is leading a national procurement exercise to introduce a new fleet of replacement high speed trains.

The test trains are expected to begin first trials on the East Coast Main Line from 2012, before a network rollout in 2015.