The train was crowded in the standard class coaches with all seats taken and some standing. The first class coaches however, were not completely full. In all there were around 500 passengers on board.

As it approached Taplow Station travelling at around 110mph, the fastenings on one of the fuel tanks came undone causing it to drop and drag along the track. The tank became ruptured spilling the diesel fuel which then ignited. The ensuing fire engulfed the outside of the front three carriages and the fire entered toilet plumbing cupboards in the two leading (first class) carriages.

Substantial amounts of smoke entered several coaches at the front of the train and smoke could be smelt further down the train. There was general concern throughout the train, with increasing desperation towards the front where passengers had to crawl along the floor due to the intensity of the smoke and fumes. A number of windows were smashed by passengers anxious to get fresh air.

The train was fitted with centrally controlled secondary door locking. This is normally controlled by the guard but can also be operated by an emergency handle at each door location. The secondary door locking was not released centrally although a number of emergency releases were operated by passengers.

As the train came to a halt a number of passengers jumped from the train on the unsafe side and made their way across the tracks to the far side. One of them narrowly escaped being hit by a passing HST travelling at speed towards London on the adjacent track unfortunately however, another male passenger... was struck and killed by this train."