A series of faults and delays has overshadowed the launch of a new high-speed train, one of 122 ordered by the government in a £5.7bn deal.
The Hitachi 800 was due to leave Bristol Temple Meads for London Paddington at 6am but did not depart until 6.25am due to unspecified "technical issues".
Passengers complained they were forced to stand for the duration of the Great Western Railway service, despite claims that capacity had been increased by 20 per cent.
They were also subjected to water leaking through the ceiling from a broken air conditioning unit. One person's laptop was damaged as a result.
The air conditioning was turned off on the train as a result, leaving commuters who had paid £204 for the standard return to the capital uncomfortably warm in the unseasonably mild weather. The service was ultimately delayed by 41 minutes.
The 800 is part of a fleet described by Transport Secretary Chris Grayling as proof "[the Government] puts passengers at the heart of everything we do," describing them as "the smartest trains in the country...probably the best we have ever had."
The Department for Transport says the new trains will cut journey times, increase the number of seats and services, and be more comfortable.
A Great Western Railway spokesman said: "Unfortunately, the train was delayed this morning due to a minor technical matter that was quickly resolved at the depot.
"The first Intercity Express Train was always likely to be popular as people seek to be a passenger on the very first train, and this did mean it carried more people than it normally would, particularly between Reading and Paddington.
"In normal conditions, this train will provide enough seats to more than accommodate the number of people that would usually travel on this train.
"We are pleased to be able to run this first train in passenger service and look forward to rolling out more trains like this in the coming months."