The sheep - 11 million in Wales alone - are stripping the uplands bare, destroying wild flowers, shrubs, trees and almost everything that grows. Now environmentalists want to turn parts of Britain's national parks into wilderness areas where plant life can return to what it was before the invasion by man and mutton.
"We want national parks to be used as they should be: as test beds for environmental ideas. There would be wilderness areas where you could withdraw all human intervention and allow everything to grow, and partial wilderness areas where the number of sheep would be reduced," said Chris Bonnington, president of the Council for National Parks, which held a conference in Newcastle yesterday on its ideas for "wilding" parts of the parks.
"Most of the national parks are desperately overgrazed. With the Common Agricultural Policy, the more sheep you have the more money you get. We have to give farmers alternatives so that less damage is done.
"With so many sheep there is no regeneration. Reduce the sheep and it is quite amazing how wild flowers, shrubs and trees start growing again."