Many modern non-lethal weapons resemble ideas from Porton Down
After Bloody Sunday in 1972 the military turned to scientists at the government's secret research centre for help.
According to recently declassified files from the National Archives, scientists at Porton Down had been looking into new non-lethal weapons for Northern Ireland since 1971.
Then they were asked to accelerate their work for use in Londonderry.
The military wanted weapons that would "incapacitate" demonstrators, allowing them to be captured.
The scientists looked at a range of possible weaponry - some of which could have come out of a Marvel comic.
These included a powerful, fast-setting glue, super-slippery road coverings known as 'instant banana peel' and powders which would rapidly stiffen clothes, making movement impossible.
The scientists were also looking for a drug which would safely knock someone out.
The scientists at Porton Down had considerable experience in this area - they had already invented CS and CR gas.
But they rejected the idea of a new knockout gas, worried that anything made people unconscious very quickly risked killing them too.
Instead, they worked on an "auto-inject dart" - to be fired from a gun - which contained either an emetic or an anaesthetic and which was based on the vet's tranquiliser dart.
One of their favoured drugs turned out to be too dangerous. Files show the medical staff advised there was "an unacceptably high risk of death" with the vomit-inducing apomorphine.
Entanglers and model missiles
Some of the inventions seem more at home in a Marvel comic
The scientists seemed to do better with their "entangler grenade", another idea they took forward.
This would explode in the air into coils of wire, landing on and immobilising protestors. The wire would be covered in fast-setting super adhesive. One idea was to add burrs which would also help trap people.
Royal Ordnance was asked to make up 1,000 of the grenades for testing but there the file ends - there is no indication of whether further tests were carried out.
A third idea was a "missile" which could take the place of the rubber bullet.
Scientists were very taken with the idea of modifying model aircraft so they could fly into a crowd at speed and knock down individuals. The cheapness of the idea was part of its appeal.
Despite some interest from military officials, there is no evidence that this idea was developed any further.
Stranger than fiction
The file is more than a curiosity. Research in non-lethal weapons has increased sharply in recent years, though the area does not get much coverage in the media.
The Moscow Theatre siege in 2002 proved that the Russians had continued to work on anaesthetizing gas. At the same time, the tragic loss of life showed that they had hardly overcome the problems identified by Porton Down scientists.
Professor Steve Wright of Leeds Metropolitan University says that ideas of 30 years ago have been realised. Porton's entangler grenade seems to have evolved into the "capture nets" that he has seen at recent arms fairs.
In the Czech republic, researchers have picked up one of Porton's rejected ideas - drugs which land on the skin, like a paintball, and knock the subject unconscious.
Professor Wright says that what was science fiction is now science fact: the US have developed heat weapons, sound weapons and devices which spark lightning into an angry crowd.
He believes there has been a "revolution" in the area of non-lethal weapons which is transforming internal security. And it has all happened with very little in the way of public debate.
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