In addition to Schedule 1 chemicals, Porton Down holds smaller quantities of Schedule 2 and 3 chemicals. The UK abandoned its offensive chemical weapons capability in the 1950s. The bulk of residual stocks of munitions and agents were disposed of at that time. Approximately 4,500kg of bulk chemical agent dating from before 1946 was destroyed between 1993 and entry into force of the CWC in 1997. In addition, from time to time, munitions suspected of containing chemical agent dating from before 1946 are found in the UK, for example, during land remediation, and brought to Porton Down.
Disposal takes place throughout the year as operational constraints permit.
In the short time available it has not been possible to establish whether, at the time of their investigation into the crash of RAF Chinook ZD576, Sir William Wratten and Sir John Day knew the extent of the Department's claim against Textron Lycoming. This litigation sought redress for faulty test procedures that caused a Chinook helicopter undergoing tests on the ground at Wilmington, USA to be severely damaged. The action taken by MOD arising out of faulty test procedures in the early days of the system's development programme had no relevance to the accident under investigation. It is therefore irrelevant whether Sir William and Sir John were aware of the litigation against Textron Lycoming. Similarly it is irrelevant whether the engineering member of the RAF Board of Inquiry into the Chinook ZD576 accident advised the other members of the Board about the test at Wilmington.