Hitachi has been chosen to supply a fleet of new intercity trains as part of a four-year contract extension agreed between First Group and the Department for Transport (DfT) for the Great Western Main Line.

Subject to final approval from the DfT, First Group has pledged to replace Intercity 125 units currently operating from London Paddington to Plymouth and Penzance with 29 new bi-mode AT300 units.

Hitachi has said the new trains, which consist of seven nine-car and 22 five-car vehicles, will be “closely related” to the Class 800 bi-mode being built for the Great Western and East Coast main lines. The new units will feature larger fuel tanks and up-rated power packs to allow it to negotiate the steeper gradients.

Mark Hopwood, Managing Director of First Great Western, said: “The fleet currently running on routes in the South West of England, is nearly 40 years old, and passengers would greatly benefit from brand new, highly comfortable trains.

“FirstGroup has conducted a competitive procurement exercise for these trains and we are close to securing private financing for the deal shortly. The DfT will be making a final decision by the end of June.”

The franchise extension will see First Group continue to operate trains on the GWML until April 2019. The direct award will return £68 million to the Treasury in premiums.

Transport Secretary Patrick McLoughlin said: “I am determined that passengers in the West, Thames Valley and South Wales get a railway that is fit for the 21st century. This is a fantastic deal which will give them more seats, more services and brand new fleets of modern trains.”

First Group chief executive Tim O’Toole said: “We are already working closely with the DfT and Network Rail to deliver the initial phases of the £7.5 billion Great Western Main Line modernisation programme. This investment is the biggest on the route since Brunel, and will transform a key part of the country’s transport infrastructure.

“Under our experienced management, the franchise will see new or refurbished trains on every part of the network, resulting in more frequent and faster journeys and an increase in the number of seats. These, and a range of further passenger benefits, will keep people moving and communities prospering between London and the South West.”