Ronald Maddison died after an experiment at Porton Down

Ronald Maddison, 20, from County Durham, died after being exposed to sarin at Porton Down in Wiltshire.

The original inquest in 1953 ruled that Leading Aircraftman Maddison's death was caused by misadventure.

In 2002, the High Court quashed that verdict and ordered that a new inquest should be held.

After hearing 64 days of evidence, the jury concluded that the cause of Mr Maddison's death was "application of a nerve agent in a non-therapeutic experiment".

An MoD spokesman said: "The Ministry of Defence notes the jury's findings and will now take some time to reflect on these.

It was Russian Roulette, Ronald Maddison was just the first... they have got away with murder

Terry Alderson, 74, Porton Down veteran

"We will be seeking legal advice on whether we wish to consider a judicial review.

"We don't believe the verdict today has implications for other volunteers. However, we will consider the implications."

The original inquest was held behind closed doors "for reasons of national security".

Volunteer Terry Alderson, 74, said outside the court: "It was Russian Roulette, Ronald Maddison was just the first.

"Reading between the lines they have got away with murder - our health was never monitored afterwards and nobody knows how many died.

'Cold research'

"This shows what liars (the MoD) were - nobody volunteered for these tests. We were sent in there like sheep."

Family lawyer Alan Care said: "We would now join with the Porton Down veterans in calling for a public inquiry."

Mr Maddison's family claimed he was tricked into taking part in the tests, and was told he was helping to find a cure for the common cold.

We would now join with the Porton Down veterans in calling for a public inquiry

Family lawyer Alan Care

Mr Maddison was exposed to 200 milligrammes of sarin which was dropped on to a piece of uniform material wrapped around his arm.

The second inquiry was prompted after ex-serviceman Gordon Bell complained to Wiltshire Police that he had been duped into similar tests.

The constabulary launched Operation Antler which looked at experiments using chemical and biological agents at Porton Down government research centre between 1939 and 1989.

The operation found that the coroner at the original inquest was "not apparently provided with all the potentially available material".

The outcome could lead to legal action by veterans of Porton Down who claim they were duped into taking part in similar dangerous trials.

The hearing, at Trowbridge Magistrates' Court, lasted six months.