“The King’s Cross fire began at approximately 19:30 on 18 November 1987 at King’s Cross St Pancras tube station, a major interchange on the London Underground. As well as the mainline railway stations above ground and subsurface platforms for the Metropolitan, Circle and Hammersmith & City lines, there were platforms deeper underground for the Northern, Piccadilly, and Victoria lines. The fire started under a wooden escalator serving the Piccadilly line and, at 19:45, erupted in a flashover into the underground ticket hall, killing 31 people and injuring 100.
The inquiry found that the fire was most probably caused by a traveller discarding a burning match that fell down the side of the moving staircase on to the running track of the escalator. The police decided that the fire had not been started deliberately, as there was no evidence that an accelerant had been used and access to the site of the fire was difficult. Investigators found charred wood in eight places on a section of skirting on an escalator and matches in the running track, showing that similar fires had started before but had burnt themselves out without spreading.
The 30° angle of the escalators was discovered to be crucial to the incident, and the large number of casualties in the fire was an indirect consequence of a fluid flowphenomenon that was later named the trench effect, a phenomenon completely unknown before the fire.”