An inquest into the death of a young airman who died in secret nerve gas tests 51 years ago has been adjourned until next month.

The hearing into 20-year-old Ronald Maddison, who died after being exposed to sarin in 1953, is now in its 12th week.

Wiltshire Coroner David Masters decided to release the jury at Trowbridge yesterday to give them a break before returning on August 23.

Leading Aircraftman Maddison, from Consett, County Durham, collapsed and died within minutes of having 200mg of sarin drops put on his arm in a chamber at the top secret Porton Down base on Salisbury Plain.

The original inquest was held behind closed doors ''for reasons of national security'' - a decision made at the highest level in the 1950s - but has been reopened after years of campaigning against its open verdict. Lawyers say the outcome could lead to legal action by Porton Down veterans.