A 41-minute delay and faulty air conditioning marred the debut of a new train carrying the Transport Secretary.

The Hitachi-built Intercity Express trains, carrying Chris Grayling, was due to set off at 6am from Bristol Temple Meads to London yesterday, but actually left at around 6.25am and arrived 41 minutes late.

Others on board the Great Western Service included rail industry bosses and regular commuters. There was also a leak from an air conditioning unit.

A GWR spokesman said: “Hitachi will be investigating." The Japanese company apologised to passengers for any inconvenience caused.

“We are of course disappointed with an issue with this train’s air conditioning and water ingress in one of the carriages. We are investigating this as a matter of priority and will restore the train back into passenger service once fully rectified.”

Some 122 of the new Class 800 Hitachi trains are due to be in service on GWR and Virgin Trains East Coast services by 2020, replacing the Intercity 125 fleet.

They are capable of running at 140mph, although will be limited to 125mph without tracks being upgraded.

The trains will also have to switch from electric to diesel power from Maidenhead to Bristol due to Network Rail’s delayed project to electrify the route.

More than 4,000 extra seats into London Paddington during the morning peak will be available from next year, with an additional 12,000 seats into London King’s Cross available by the end of 2020.

Mr Grayling said: “This Government is investing record amounts to modernise Britain’s rail network and give passengers the faster, more comfortable trains and the better journeys that they expect.

“These new state-of-the-art trains show our commitment to put passengers at the heart of everything that we do.”