Richard Porter, a professional ornithologist and conservationist from Cley, thought it would be a bad move for bird life, people and the tourism industry not to repair the breaches.

He said: 'I think it would be a disaster to have salt water coming into what were fresh water marshes, because it would decrease the bio-diversity and particularly the bird life. Salt marsh is very rich too but is not so bio-diverse and there's plenty of salt marsh along other stretches of the Norfolk coast.'

Mr Porter, a member of Cley bird club, said thousands of people flock to the north Norfolk coast to spot species including lapwing, red shank, marsh harrier, avocet and bittern, which use the fresh water grazing marsh. If it were to become salt water marsh, he said these birds would not come to breed.

'Birdwatchers and tourists come here every year because of the diversity of bird life created by the fresh water,' he added. 'I think leaving things and letting nature take its course, from a bird conservation point of view and for the conservation of other wildlife, would not be very sensible.

'I do hope the National Trust and Norfolk Wildlife Trust are given every support to negotiate with the Environment Agency for the breaches to be filled in, in the most sensible way. I cannot see them being fixed by allowing natural processes.'