John, the veteran farmer beside her in his lambing shed at this East Sussex farm, says grimly: ''He's getting cold now. I will have to shoot him. It's not easy.''

This is one of 74 farms across England that have been struck by a new disease that is causing thousands of lambs to be born dead or with deformities that mean they cannot survive for more than a few minutes.

A thousand farms across Europe have been hit in the last month or so - but nobody knows how bad things will get, because the lambing season is not in full swing. The disease is invisible in sheep until the infected ewes give birth.

Schmallenberg disease is so new it was named only in December, after the town in western Germany where the first cases were seen last August in dairy cows.

Scientists are not sure how it is transmitted, but the leading theory is that plumes of midges carrying the disease were blown across the sea in autumn. Sheep have a gestation period of five months, so the adults infected then are beginning to give birth now.