clipped from: news.bbc.co.uk 
Lethal clouds of tiny poisoned darts were to be tipped with mustard gas to kill enemy troops without damaging nearby buildings or equipment.
The concept was developed between 1941 and 1945 at the Porton Down research base in Wiltshire.
Research scientists thought clouds of poison darts, blasted from canisters high above the battlefield, could be even more lethal against enemy troop concentrations than high-explosive shells.
Mustard gas compounds in the needles would ensure anyone whose skin was broken would die a swift and horrible death, or at least have terrible injuries.
"But it shows the Allies were prepared to consider anything - no matter how gruesome - to secure a victory."
The file shows the darts were never used because they were a "highly uneconomical weapon" and only a small proportion of people would have been killed.