The Harrow and Wealdstone rail crash was one of the deadliest railway accidents in British history, occurring due to a series of catastrophic collisions that began when a local passenger train hit the rear of a stalled freight train. The incident unfolded early in the morning on a busy line in Harrow, London. Following the initial impact, a high-speed express train collided with the wreckage, exacerbating the death toll. The collisions resulted in an estimated 112 fatalities and hundreds of injuries, making it a significant event in the annals of transportation disasters.

Rescue operations were immediately launched, with emergency services responding from all over London. The scale of the disaster called into question the safety protocols in place at the time, especially regarding signals and the operational procedures for trains on the same line. Investigation highlighted that the signals had not been properly adhered to, contributing to the catastrophic sequence of events.

In the aftermath, British Railways undertook a comprehensive review of railway safety measures. The crash spotlighted deficiencies in signaling technology and operational practices, leading to extensive reforms in safety regulations throughout the UK railway network. These changes formed the basis for modern safety standards and protocols that are still in place to this day.