MEDICAL experts giving theories on the unexplained death of schoolboy Nathan Matthews during a swimming lesson said yesterday it was unlikely drowning was the primary cause.

The inquest at Oxford Coroners' Court heard from three consultants who tried to determine why the 11-year-old drowned during a school swimming lesson at Thame Leisure Centre on July 12, 2004.

All of them agreed drowning was likely to have been a secondary cause of death as a result of an event such as a cardiac arrhythmia - a sudden heart disturbance - or some kind of fit or brain seizure.

The inquest continues.