Eight-year electrification programme will upgrade 300 miles of track on Britain's busiest railway line
The government is to spend over a billion pounds to electrify the London to Cardiff railway, over 300 miles of track.
The £1.1bn programme is set to take eight years and will reduce carbon emissions as well as making the service more efficient.
Running through Oxford, Reading and Newbury, the line is Britain's busiest. Electrification will shorten a journey to Swansea by 20 minutes.
Announcing the move this morning, prime minister Gordon Brown said that electrification was an important priority and that money had been set aside for the project.
It will allow the replacement of Intercity 125s with express trains.
The government is also spending £100m to carry out similar work on the line between Liverpool and Manchester over the next four years.