Eurotunnel was unable to explain exactly why there were 29 lorries, rather than the usual 28 on the the train. A spokesperson said: "It may be that one of the wagons had two smaller vehicles on it." The 31 drivers and passengers - who included a seven-month pregnant girlfriend of one of the truckers - were all sitting in the Club Car behind the front locomotive. There were also two crew, the chef de train and the stewardess who serves the meals to the truck drivers.
Behind them were 28 freight wagons, four loaders, and the second locomotive at the rear, a train of 700m in all.
Denis, a young French lorry driver who lives in Scotland, said that he noticed something amiss early in the journey: "About 200 or 300m into the tunnel, the Shuttle braked and almost stopped, then set off again."
As a regular user of the tunnel, he said he found this unusual. But the first thing Emile Grard, the chef de train, noticed wrong was when he was alerted simultaneously by a visual and sound alarm, set off by sensors, and by a call from the British controller. Mr Grard immediately followed the emergency procedures, telling the driver to try to continue to the English side.
He told French press agencies yesterday from his hospital bed: "The moment the alarms went off, I pressed the button telling the driver to increase speed to 100kmph."
However, there is confusion about what happened next, with some reports suggesting Mr Grard told the driver to hit the emergency button to stop the train. It came to a halt just over 11 miles from the French end, 20 miles from the English side, at around 9 04pm British time. It could not reverse because there was another train behind it.
As soon as the train stopped, conditions in the club car deteriorated, with smoke getting in - possibly because the door was opened in an attempt at evacuation.
Denis said he had used four or five paper napkins to keep the smoke at bay; he had trained as a deep-sea diver, so knew how to control his breathing. "But another two minutes would have been impossible."
Jeff Waghorn, 32, from Westcliff-on-Sea, Essex, said he and other drivers lay on the floor of the passenger compartment fearing they would not get out alive. In an attempt to avoid inhaling fumes, they held damp napkins to their noses for about 10-15 minutes. "We were getting light-headed. Another five minutes, I think there would have been a proper disaster," he said.
It is unclear why the passengers were not evacuated straight away. It could be that fans at either end of the tunnel are supposed to come into operation to blow smoke away from any passengers, allowing them to escape into clean air. However, it is clear from the reports of the drivers that this did not happen and they were forced to escape into the service tunnel which runs between the two main tunnels.
Mr Grard said that he had evacuated the club car before the rescuers arrived. "It was improvisation that saved us. We followed the instructions, but there was a point where we had to start improvising ... I did as much as I could. I hope that I saved some lives,' he said.
He said when the train stopped, the tunnel was full of smoke and the lights went out. "It was only when we got into the emergency tunnel that we saw the firemen. That's when I fainted."
The next thing he knew was waking up in hospital in Lille.
Sonia Matczak, the pregnant 24-year old girlfriend of one of the lorry drivers, was also taken to hospital in Lille. She confirmed that they had left the compartment before the rescuers arrived.
"It was very fraught," she said, "but the train manager managed to calm people down and stopped one person smashing a window."
French firefighters arrived along the service tunnel around 20 minutes after the train stopped and their British counterparts arrived about an hour later, having apparently only been alerted at 10pm.
The fire, thought to have started in a lorry carrying a load of polystyrene, was still smouldering seven hours later, having caused extensive damage to the tunnel including buckled rails. The fire was not brought under control until 6am.
Mr Grard and Ms Matczak were taken by helicopter to Lille. Six people, including a female crew member, were taken to hospital in Calais; 26 others taken to a Boulogne hospital and all but five were discharged yesterday morning.