Mr Maddison was 20 when he died in 1953

An RAF man who took part in a chemical test in which his colleague died has relived the experience at an inquest 50 years on.

Leading Aircraftman Ronald Maddison, 20, died after being exposed to Sarin in May 1953 during an experiment at Porton Down, Wiltshire.

On Tuesday, Michael Cox told how he saw LAC Maddison slump forward after he was exposed to drops of deadly sarin.

The pair were among a group of six servicemen taking part in the test.

Sealed chamber

The inquest, at Trowbridge Town Hall, heard they volunteered to take part in the tests after seeing notices at their respective RAF bases.

They were tempted by the payment of 15 shillings and assurances they would come to no harm.

Mr Cox, 73, from Chandlers Ford, Hampshire, said the men had played noughts and crosses and draughts as they sat in the sealed gas chamber waiting for the sarin to take effect.

But minutes after having drops of the nerve agent applied to a strip of cloth wrapped around his arm, LAC Maddison collapsed and died.

Mr Cox said he did not learn of LAC Maddison's death until much later after he left Porton Down.

He said the experiments carried on as normal and there was no sense of alarm or panic.

The inquest continues.