Rolling stock company Porterbrook Leasing has placed an order for an additional 80 Class 387 Electrostar electric multiple units (EMUs) from Bombardier.
Worth around £100m, the new fleet of trains are in addition to the 256 Class 387 vehicles already on order, according to the Derby Telegraph.
The earlier order included four-car sets, 29 for Thameslink, 27 for Gatwick Express and eight for Great Western.
The 29 vehicles ordered for Thameslink will be moved to the the Great Western franchise when the former will receive its delivery of Siemens Class 700 Desiro City trains.
In May, Porterbrook signed an agreement with First Greater Western to supply 32 Class 387 vehicles.
These vehicles are scheduled to be delivered to the train operator between 2016 and 2017, for routes serving from Paddington to Reading and Oxford.
The new vehicles will be built at Bombardier’s Derby facility and deliveries will take place between October 2016 and June 2017.
The leasing company said the new order was placed to support the UK Department for Transport (DfT’s) aim to invest in new vehicles to satisfy increasing capacity on the rail network both in the short and medium term.
The investment decision also embraces the initiative for the Midlands Engine for Growth and supports local skills and manufacturing jobs in the region.
UK Transport Secretary Patrick McLoughlin said: "Introducing more modern, high-quality trains is central to our commitment to give passengers better journeys and boost economic growth, with more than 3,700 extra carriages set to be introduced across the network by the end of 2019."
Bombardier’s Electrostar trains are already operated across the rail network within TSGN, Essex Thameside, South Eastern and soon Great Western franchises.
Several parties, including Transport for London (TfL’s) Rail for London, have already expressed an interest in leasing the new trains.
The dual-voltage, 110mph Electrostar EMUs will be equipped with air-conditioning, two-by-two seating and the latest on-board service information and facilities for disabled passengers.