text: A public inquiry was conducted from February to June 1988. Investigators reproduced the fire twice, once to determine whether grease under the escalator was ignitable, and the other to determine whether a computer simulation of the firewhich would have determined the cause of the flashoverwas accurate. The inquiry determined that the fire had been started by a lit match being dropped onto the escalator. The fire seemed minor until it suddenly increased in intensity, and shot a violent, prolonged tongue of fire, and billowing smoke, up into the ticket hall. This sudden transition in intensity, and the spout of fire, was due to the previously unknown trench effect, discovered by the computer simulation of the fire, and confirmed in two tests on scale models.
  London Underground was strongly criticised for its attitude toward fires; staff were complacent because there had never been a fatal fire on the system, and had been given little or no training to deal with fires or evacuation. The report on the inquiry resulted in resignations of senior management in both London Underground and London Regional Transport and led to the introduction of new fire safety regulations. Wooden escalators were gradually replaced with metal escalators on the Underground.