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Crammed into small boxes, their heads wedged through tiny holes, the monkeys undoubtedly look terrified. Around them, men in rubber overalls and gas masks arrange a semi-circle of boxes containing guinea pigs on the deck of a sloping pontoon.


After the boxes have been laid out, the men disappear below the deck of a ship, and for a while, nothing happens.




Then, after several minutes, a small bomb placed on a boom a few feet out to sea detonates, and showers the animals in a deadly cloud of bubonic plague.



These scenes, which have just been released, appear in a gruesome film showing secret germ warfare experiments on animals carried out by British government scientists sixty years ago.


The experiments, which ran from May to September 1952 off the coast of the Isle of Lewis in the Outer Hebrides, exposed nearly 3,500 guinea pigs and 83 Rhesus Macaque monkeys to deadly germs such as bubonic plague.


Codenamed Operation Cauldron, the secret experiments were part of our nascent biological warfare programme, which at the time was deemed as important as the development of nuclear weapons.


Acting in the belief that the Soviets were producing bacteriological bombs, scientists from Porton Down laboratory in Wiltshire were briefed to devise similar weapons that could be used in retaliation against a Russian germ warfare strike.


Although the existence of the 47-minute film has been known about for many years, it is now available for the world to see on the video-sharing website YouTube, thanks to the efforts of Mike Kenner, 58, an Open Government campaigner from Weymouth in Dorset.




Trials: A Rhesus Macaque monkey and five guinea pigs await their fates on the deck of the pontoon



Scientists set out the animals in cages on the deck of the pontoon before a small bomb containing bacteriological agents is detonated


‘This is the only film like it in the world,’ says Mr Kenner, who lobbied the Ministry of Defence to get the film released. ‘As far as I know, it’s the only film that shows animals being exposed to deadly pathogens.’


The MoD was reluctant to release the film, and it is not hard to see why as it is disturbing viewing.


Many of the monkeys and guinea pigs exposed to the germs died within a few days, while any that survived were killed and dissected so their organs could be studied for the effects of the deadly germs.


Above all, it is the sight of the monkeys’ almost human faces that make the film so shocking.

‘Although we see the tests are being carried out on animals,’ says Mr Kenner, ‘when one sees the monkeys, one can’t help but empathise, and realise that these weapons were being designed to be used against people’.


Very few of those who took part in Operation Cauldron are still alive.


One of the men who can testify to the truth of what happened is Geoffrey Scarlett, 82, who was a petty officer on board the ship the Ben Lomond, which housed the animals and scientists.


As the ship’s writer, responsible for sending back reports to the Admiralty, Mr Scarlett well understood the aims of the project. Many of the other sailors only had a vague idea of the experiments being carried out on the nearby pontoon.



The terrified monkey are sealed in small boxes in the hold of the pontoon before being brought up on deck in batches to exposed to deadly germs




Fate: Many of the monkeys and guinea pigs exposed to the germs died within a few days, while any that survived were killed and dissected so their organs could be studied


‘We were simply told that we were going on a germ warfare trial,’ says Mr Scarlett. ‘But we were not told where we were going.’ However, the men were informed that taking part was not compulsory.


‘Right from the beginning, they let anybody know that if they objected to the experiments being carried out on animals, then they would be allowed to drop out and there would be no stain on your record,’ says Mr Scarlett.


‘To my knowledge, nobody dropped out. You have to remember these were different times and animal welfare was not such a priority.’


Mr Scarlett also says most saw the necessity for the development of a new type of weapon of mass destruction.


‘It was the middle of the Cold War,’ he says. ‘You realised that it had to be done. Most had served in the war, or, like me, had been brought up during the war. We had seen the atomic bomb, and this was another type of warfare.

‘In theory, it was going to be a lot more deadly than nuclear warfare. A nuclear bomb can take out a city. Germ warfare can take out a country.’


The utmost care was taken to keep the experiments safe and wind conditions were carefully monitored before each detonation to avoid spreading the germs inland.




A scientist prepares for an experiment. Around 3,500 guinea pigs and 83 Rhesus Macaque monkeys were exposed to deadly germs


However, there was one accident that could have had disastrous consequences.


On the last day of the programme, a trawler, the Carella, sailed through the path of a bubonic plague experiment.


‘The trawler was tailed by two naval vessels for 21 days, waiting for any distress call,’ says bacteriological warfare expert Dr Brian Balmer of University College, London.


‘When none came, almost all records of the incident were burnt.’ Indeed, the crew members only heard about their exposure to the plague when the official records were opened 50 years later.

When the scientists involved in the trials returned to Porton Down, they judged the experiments to have been a success.


‘New ground has been broken with plague trials,’ read a report.


But the findings of Operation Cauldron were never meant to come to the public’s attention.


If the experiments ever did come to light, the then Prime Minister, Winston Churchill, had prepared a statement justifying what many would have regarded as unethical.


‘The possibility that bacteria may be used in a future war cannot be overlooked,’ the statement read

‘The researches...are being pursued so that defensive measures may be taken. The experiments now taking place form part of these researches.’


Today the MoD has sought to distance itself from the experiments. It says it does not recognise the treatment of animals as seen in the film as being in line with modern ethical scientific conduct.


Although it is unlikely such creatures are today being exposed to deadly pathogens in the pursuit of military advantage, the release of the film is a chilling reminder of the disquieting lengths Britain went to develop perhaps the most deadly weapons the world had ever seen.


Original 1952 MoD video WARNING: GRAPHIC CONTENT