A train was pulled out of service in Oxfordshire on Monday afternoon as staff said it was 'too hot to go on' while Britain sizzled in its hottest May day ever.
Passengers were forced off the 4.37pm service from London Marylebone to Stourbridge Junction, West Midlands, after the air conditioning system broke down on board.
Staff handed out water bottles and the train was emptied at Banbury as travel chaos continued as the country baked over the bank holiday weekend.
Video from one of the stricken carriages showed passengers asking 'what's going on?' as they were told they would need to leave before their destinations.
A man could be heard saying: '45 degrees and no air conditioning.'
Another seemingly said: 'Leaves on the track would be too hard. Normal in the UK now.'
The five-coach service had left Marylebone station three minutes late, at 4.40pm, before arriving in Banbury, its second stop, at 5.42pm, where it terminated.
On the National Rail website, the service was displayed as 'running late because of a fault on this train'.
Passengers were forced off the 4.37pm train from London Marylebone to Stourbridge Junction because of the heat
Digital displays showed the message: 'This train is not in service.' This was despite the train still moving along the tracks.
During the two-hour, 25-minute service the train had been due to call at nine more stops: Leamington Spa, Warwick, Warwick Parkway, Dorridge, Solihull, Birmingham Moor Street, Birmingham Snow Hill, Rowley Regis and Stourbridge Junction.
As confused passengers turned to alternative arrangements, the in-carriage digital display read: 'This train is not in service.'
This was despite the train still being on the move.
The Daily Mail contacted Chiltern Railways for comment.
National Rail warned passengers that major engineering work was due to take place until Monday evening, with disruption to routes across the Gatwick Express, Southern, Thameslink and South Western Railway networks.
Oxfordshire was one of nine counties where temperatures rose above 32C on Monday amid a 'historic' bank holiday heatwave.
Tens of thousands of Britons flocked to the coast and beauty spots to enjoy the searing heat despite official government guidance to stay out of the sun during the day's hottest hours.
London's Kew Gardens recorded 34.8C, beating the previous hottest May day of 32.8C in 1944.
The Met Office said the bank holiday heat was 'exceptional in the UK even in mid-summer, let alone in May'.
Wales saw its hottest ever temperature in May on Monday evening, with 32.2C recorded at Hawarden Airport in Flinshire. The previous record of 30.6C in Newport stood for 82 years.
Up to nine counties, including Oxfordshire, Greater London, Surrey and Norfolk, saw temperatures soar above 32C - and the Met Office forecasted temperatures could yet climb to 35C on Tuesday.
Amber and yellow health alerts remained in place across England on Monday evening amid what the Met Office has described as an 'unprecedented' heatwave for this time of year.
Temperatures of up to 34C were still beating down on England by 4pm
Tourists and families cooled off in the sea at Bournemouth beach on the hottest May day ever
The warnings came as a man died on the beach in Hastings, East Sussex, following a 'medical incident', and a 15-year-old boy drowned at Swanholme Lakes in Lincoln on Sunday.
On Monday, beaches across the country were full of sunseekers while others descended on lidos and parks as they made the most of the final day of a scorching weekend.
Tom Morgan, a Met Office meteorologist, said: 'We rarely see temperatures above 35C, even in the summer months, so to see temperatures getting close to 35C in May is, as I say, pretty historic.'
The Met Office said the warm spell has been driven by the development of high pressure over the country that caused air to sink, compress and heat.
Scientists said the record-breaking heat is a stark reminder of how the climate crisis is impacting lives in the UK.
More heatwaves are expected across the summer due to the developing 'super El Niño'.
The phenomenon, which supercharges weather events - for example making heatwaves hotter - is predicted to hit in 2027 but is expected to begin emerging this summer.
The Met Office said eight regions officially entered heatwave conditions on Sunday after three days at or above the temperature threshold.
They were Heathrow in Greater London, Benson in Oxfordshire, Brooms Barn in Suffolk, High Beech in Essex, Kew Gardens in London, Northolt in London, Santon Downham in Suffolk and Writtle in Essex.