In the early evening of 8 August 1996, a Class 321 passenger train operated by Network SouthEast travelling from London Euston on the West Coast Main Line Down Slow line at around 110 km/h (68 mph) passed a signal at danger. Having applied the brakes it eventually stopped 203 m (222 yards) past the signal and was traversing the junction between the Down Slow line and the Up Fast line. An empty Class 321 coaching stock train approaching at roughly 80 km/h (50 mph) collided with the stationary passenger train approximately 700 m south of Watford Junction whilst progressing across the connections from the Up Slow line to the Up Fast line.