AN Oxford commuter has claimed that a Chiltern Railway service this morning had no air conditioning, leaving passengers sweltering in 'sauna'-like surroundings.

The passenger, who asked to remain anonymous, suggested that the delayed 10.06am service from London Marylebone to Oxford was 'absolute torture'.  

They explained: "The train did not have any operational air conditioning on board.

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"With the outside temperatures of [around] 39 degrees and even hotter inside, it was an absolute torture to travel."

Train passengers have been told to expect delays and only travel if necessary today, as Britain bakes in a heatwave. 

The passenger added: "It was announced through the intercom that one carriage was air conditioned. Some passengers tried to move there at the expense of being forced to stand right next to each other with no breathing room.

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"They soon found out that the conditioning wasn't working there either. It was also impossible open the windows as the train wasn't built in such a way as to allow for this.

"To add an insult to injury, the toilets were out of order as well. Passengers were suffocating and someone tried to call Chiltern railways, however it was impossible to get a hold of anyone."

Chiltern Railways spokeswoman Laura Jones said: "We’re sorry some customers have experienced uncomfortable journeys today, we are working as hard as we can to ensure that all our trains have working air cooling systems. In particularly hot conditions like today, it can become less effective.

"Where a fault develops our engineering team work quickly to resolve the issue and we provide free water for passengers on such services where possible. We encourage passengers to close the carriage doors behind them when they enter and exit the train to make the system as effective as possible.

"We are also advising customers on how to keep cool via our social media channels including carrying water and staying hydrated, making space for everyone by stowing luggage in overhead racks and alighting at staffed stations and seeking assistance from staff or 24-hour help points if feeling unwell."