First Great Western could be converting some of its first class seats in a bid to get more passengers on board.
The company believes it can increase capacity by 16 per cent on its train by converting some of the first class lounges.
The first class seats are said to generally be no more than 70 per cent full.
The company believes it will be crucial to boosting the network capacity.
It will mean an extra 3,000 seats on high-speed services into London during peak times and the first converted carriages will be finished in June.
The entire fleet, servicing the south west, including Gloucestershire, will be completed by summer 2015.
A standard carriage contains 80 seats - 32 more than a first class carriage.
The company’s high speed trains are made up of either six standard and two first class carriages, or five standard and 2.5 first class carriages.