South West Trains, which operates the service, has said the £210m set of new trains will mean 18,000 extra peak-time seats for passengers travelling into Waterloo.

Longer trains will also be a feature on the service from Reading, which runs through Winnersh, Wokingham and Bracknell.

The rail operator has awarded the contract for the 150 new train carriages to technology firm Siemens and leasing company Angel Trains.

The move has come after the number of passengers using South West Trains services has increased by more than 100% over the last 20 years and now more than 222 million passenger journeys are made over the operator’s network across the south and south west.

The first of the 30 new five-carriage Desiro City trains will begin arriving in 2017, with the remaining trains in service by early 2018.

Tim Shoveller, chief executive for the South West Trains-Network Rail Alliance, said: “These exciting plans will deliver the biggest step-change in capacity and service to our customers on the network in decades.

“As well as providing extra space for passengers using our services now, the combination of investment in the infrastructure and these new trains will create space at Waterloo that is the essential first step to allow an increase in capacity for our longer distance, mainline services.” The announcement is part of a five-year plan by the alliance to improve services, including the purchase of 108 additional refurbished carriages, longer platforms, the full re-opening of platforms at the former Waterloo International Terminal and other infrastructure projects.

Steve Scrimshaw, managing director at Siemens Rail Systems, said: “The new Desiro City trains will transform the lives of passengers travelling on south-western England’s rail network. No other train in the UK is as technologically advanced and offers as many benefits in terms of passenger environment, capacity and reliability.”