Trains from Cardiff to London run regularly from Cardiff Central train station to London Paddington train station. Trains are operated by a company called First Great Western.
In general, trains leave Cardiff Central Station for London Paddington station every half hour at 25 and 55 minutes past the hour. Trains from London to Cardiff return every half hour at 15 and 45 minutes past the hour.
Weekend, late evening, and early morning trains from Cardiff to London sometimes run less frequently and often have a longer journey time.
Most trains on this route are direct and do not require any changes on the way. Some trains require one change en route, but they take almost an hour longer. It is best to avoid them if you can.
The total journey time from Cardiff to London is between 2 hours, 5 minutes, and 2 hours, 13 minutes, depending on which train you take.
Ticket fares for trains from Cardiff to London start at 11.50 GBP for singles if you book on the Internet in advance. Buying train tickets online ahead of time will save you money, as fares increase the closer you get to the date of travel.