The Ministry of Defence's announcement that it is to award 3m in compensation to 360 veterans of chemical weapons tests has put the spotlight on the Science and Technology Laboratory at Porton Down. 1916: Building work begins at Porton Down ... to create an experimental base for research into chemical warfare. 1920: Large-scale expansion of the site begins, initially focusing on the effects of mustard gas - experiments in which thousands of volunteers were to participate. 1940: After the outbreak of war, a secret group is set up at Porton Down to investigate biological warfare. 1945: Thousands of military personnel had taken part in trials at Porton Down during World War II. As the war ended, volunteers began participating in nerve-agent trials there - a practice that was to continue until 1989. 1953: Leading Aircraftman Ronald Maddison participates in chemical experiments at Porton Down. Within an hour of being given sarin, he is dead. Military chiefs conduct an inquest in secret. Verdict: misadventure. 1989: Nerve-agent trials at Porton Down cease. 2002: Ministry of Defence (MoD) helpline set up to enable Porton Down veterans to find out more about the trials they were involved in. 2004: Fresh inquest into the 1953 death of Ronald Maddison returns a verdict of unlawful killing. The MoD [only two years later] admits gross negligence". 2008: The BBC learns of a 3m out-of-court settlement between the MoD and veterans, under which the [360] ex-servicemen will each receive 8,300 and an apology ... without admission of liability.