A new train service between Wales and London could be launched within three years.
Prospective operator Grand Union Trains (GUT) said it wants to run five daily return services between Carmarthen, south-west Wales and London Paddington from 2025.
It has submitted an application to regulator the Office of Rail and Road for permission to run the services on an open access basis in competition with Great Western Railway.
The Government issues contracts for most train services on Britain’s railways, but there are four open access operators, which do not receive subsidies from the Department for Transport.
They are Grand Central, Heathrow Express, Hull Trains and Lumo.
GUT’s bid involves building a new station at Felindre – next to the M4 motorway to the north of Swansea – which would reduce journey times from Carmarthen and Llanelli to Cardiff and on to London by around 20 minutes.
A fleet of new bi-mode trains which can be powered by electricity or diesel would be used.
Passengers would benefit from “best experience in the market” with bigger seats, more legroom, increased luggage space and a buffet car on every service, according to GUT.
The project is being developed in partnership with European investment company Serena Industrial Partners and Spanish train operator Renfe.
GUT managing director Ian Yeowart said: “We have been pleased to work on promoting this important service which will, for the first time, deliver significant new infrastructure as part of the application process.
“Our high-quality offer will undoubtedly improve the user’s experience while using the UK rail network, a worldwide rail reference that continues to evolve every day.
“For this goal, we have been proud to work alongside colleagues at Serena and Renfe whose vision for improved services is close to our own and has enabled us to put forward this ambitious project to the ORR.”