A collapsed man was airlifted to hospital on Bank Holiday Monday.
An ambulance was called at 7.45am after a man in his 60s collapsed near the A131.
He was flown to Queen’s Hospital, London by the Essex Air Ambulance.
A spokesperson from the ambulance service said: “He is still in a serious condition.
“It is not known what caused him to collapse but further tests will be carried out in hospital.”