The first year's shearing yields the softest wool, and so lambswool has always been highly prized. Lambswool from the Merino sheep is the softest wool of all. Merino sheep were first bred in Spain, and to protect the fine wool trade the sheep themselves could not be exported. Eventually in the 18th century flocks were established in England and then Australia, with the wool being imported to the weavers of England through the great port of Bristol. It's insulating properties help regulate body temperatures, providing warmth without over heating.