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.

The person who was killed was Ruth Holland, book review editor of the British Medical Journal.

[2] As a result of this accident, the train driver was charged with manslaughter by the Crown Prosecution Service on 10 January 1997, following an investigation by the British Transport Police.

In its report, the Health and Safety Executive (HSE) advised that there was insufficient evidence to justify legal proceedings against the other involved parties, namely Railtrack and Network SouthEast.

Following delays caused by the criminal proceedings against the driver, the HSE and the Office of Rail Regulation jointly published its Report into the railway accident at Watford South Junction on 8 August 1996[3] on 29 April 1998, a summary version was published on the internet on 21 May 1998.