Lord Melchett was policy director at the Soil Association from 2002 until his death.

Its chief executive Helen Browning said: 'We are so saddened by the death of Peter Melchett, policy director at the Soil Association and true champion of the organic movement.

'Peter was such an important, charismatic figure in the environment and organic movement throughout his lifetime.

'He was an extraordinary man with incredible knowledge across a wide range of subjects, ranging from beef farming to sustainable cosmetics.

'A true campaigner all his days, he will be greatly missed by all his Soil Association colleagues.'

Norfolk-based campaigner Jessica Lonsdale, who worked for Greenpeace in the 1970s and went on to form the Environmental Investigation Agency, said: 'Peter was a passionate campaigner for the environment. He stood up for what he believed in, he practised that in his own farming and his campaigning with Greenpeace for many years. He's going to be greatly missed. We need people like Peter.'