The Rail, Maritime and Transport union claims that new £4.5 million trains running from London to Cardiff will be slower than the trains provided by British Rail (BR) over 40 years ago.
According to research conducted by the union, services in the 1970s were faster than those advertised by Great Western Railways (GWR).
GWR promises a train journey time from London to Cardiff of 113 minutes, which is slower than the 105 minutes under British Rail in 1977.
RMT general secretary Mick Cash said that the union’s findings reveal the failures of rail privatisation.
Mr Cash said: “Privatised rail services are not only more overcrowded and expensive they are also slower.”
“And of course as well as being publicly owned, British Rail trains were publicly manufactured for far less cost in the UK, as opposed to the new IEP trains which are manufactured in Japan.”
GWR said that transport union claims are incorrect
However, GWR said that the unions facts are incorrect, adding that the RMT was not comparing like with like.
In a statement said GWR said: “The fastest Bristol-London journey time, quoted by the RMT, in 1977 was one hour 25 minutes. Following electrification and the new trains, this will be one hour 19 minutes, that’s six minutes faster than in 1977.
“In 1977, six trains ran every two hours between Cardiff-London and Bristol-London, compared to 12 trains every two hours following electrification and the introduction of new trains. That’s double the number of services.
“The fastest Cardiff-London journey time, quoted by the RMT, in 1977 was one hour 45 minutes. This will be the same with the introduction of electrification and new trains.
“However while there was around one train per day that achieved one hour 45 minutes in 1977, after electrification and the introduction of new trains there will be at least three trains a day between the two cities that achieve that time, and the majority of others will offer competitive timings.
“These trains will call at more stations than they did in 1977.
“The fastest journey between Swansea-London in 1977 was two hours 43 minutes, compared to two hours 38 minutes after electrification and new trains.”