The event, lasting several hours and involving about 500 police, fire brigade, ambulance and London Underground personnel, was intended to prepare the emergency services for mass decontamination in the event of a chemical, biological, radiological or nuclear attack.
Eventet varede adskillige timer og involverede omkring 500 politi-, brand-, ambulance- og London Underground-ansatte, og havde til formål at forberede alarmberedskabet på massedecontamination i tilfælde af et kemisk, biologisk, radiologisk eller radioaktivt angreb.