The recent Sunday Herald story has once again reminded us of the notorious biological weapons tests that took place on board the Ben Lomond off the coast of North Tolsta , Lewis, in the early 1950s.

These experiments were first revealed almost 10 years ago in Parliament as part of a fuller account into British and American activities during the Cold War. Questions about these experiments were asked at that time by a Labour colleague, Harry Cohen MP.

The response to Harry's enquiries, in January 1994, revealed the startling information that biological weapons tests had been conducted in the North Minch . According to the Ministry of Defence, Operation Cauldron, conducted between May and December of 1952, “established that several pathogens could constituent a hazard if used as BW agents”, and Operation Hesperus, between May and August of 1953, “aimed to consolidate data and compare several dissemination and collection methods” for such weapons.

After this information came out, I wrote to the Government to obtain further information about the tests and, in particular, to clarify what safety issues were involved at the time and, indeed, today. The first reply I received was dated 21 st February 1994, from Dr Graham Pearson, the Head of Porton Down, the MoD's Chemical & Biological Testing Establishment. Dr Pearson refused to publish the technical papers relating to Operations Cauldron and Hesperus because “it would not be in the national interest to make these available as the information therein could be misused by states seeking to acquire a biological weapons capability.” However, he confirmed that the pathogens used were brucellosis and plague in the 1952 tests and brucellosis and tularaemia in 1953. The latter pathogens are debilitating but rarely fatal. The plague bacteria, however, has the potential to kill huge numbers of people. As for safety, Dr Pearson stated baldly that “the safety aspects of handling, transport and packaging were all carefully addressed to ensure that there was no danger to any of those engaged in the trials whether on land or at sea. There is no cause to believe that there was any hazard to the public or the environment, and there is no evidence to the contrary.”

This was a bald attempt at reassurance but without any accompanying explanation. So at the end of February, I wrote again to the Secretary of State for Defence pressing him on the safety issue and asking why Dr Pearson could be so confident. The then Defence Minister, Jeremy Hanley MP, replied on 12 April 1994 and said, “it is important to recognise that both Operations Cauldron and Hesperus involved the use of biological agents which are fragile living organisms that rapidly die in the natural environment ” (the Minister's underlining). He went on: “The living micro-organisms used in the trials started to die naturally as soon as they began their downwind travel. In addition, the agent would be diluted continuously to an increasing extent in the atmosphere so that the concentration rapidly dropped below one that might present any danger. Finally, gravitational forces would cause agent particles to be deposited on the sea. Any agent particles falling into the sea would be massively diluted as well as killed by the bactericidal and virucidal effects of the sea water.”

Thus, according to the MoD, “dilution into the atmosphere, deposition of particles into the sea and the progressive decay of the micro-organisms with ensuring loss of viability and infectivity meant that the biological agent aerosols have a finite life. In effect, the biological agents ceased to exist after some period of time and distance downwind.” The mention of aerosols is a reference to one of the means by which the biological agents were exposed, the other being by small explosions.

In addition, the Minister said, “conditions were selected for these trials and downwind safety areas delineated from which shipping was kept away to ensure that there was no hazard to the public or to the environment”, although one fishing boat had strayed into the keep-out zone. The Minister concluded: “I am therefore content with Dr Pearson's conclusion that there was and is no hazard to the public or the environment.”

According to the MoD, these were the only two tests carried out at sea by the UK since the Second World War, although there had been trials in Scapa Flow in 1923 of a chemical agent. After the two Minch tests, further tests were re-located to the vicinity of the Bahamas . In the 1950s, the UK abandoned all offensive chemical and biological weapons. Porton Down has continued to conduct research but this has been designed to ensure that UK Armed Forces have effective protection against the threat that chemical or biological weapons might be used against them, for example, the development of the chemical weapons suits carried by the Army in Iraq .

It would certainly be interesting to hear from anyone who can remember the Ben Lomond and the rumours surrounding its activities at the time.

Calum MacDonald MP

9 July 2003