I stroked one of the wound balls of yarn, and thought of all the good things of sheep: milk, and cheese, and greatest of all, wool; and I thought too of the making of parchment, and that without a lambskin I could not make any, and so could not send to Ælfwyn's parents the letter I had promised. 

She seemed to read my thoughts, for she said, "Can it be true that no sheep are left here? How will the people live without sheep? How even will we live? If the Danes are to stay here and make Lindisse their home, surely they know they must farm and raise sheep." 

The Circle of Ceridwen, Chapter the Twenty-fifth: The Weaving of Life 

LIFE without sheep was unthinkable. For the average Anglo-Saxon, sheep meant sustaining meat, milk, and cheese, healing wool-wax, valuable parchment, and most vitally, fleece. Fleece to be shorn or pulled, and spun and woven into cloth. Recall that there were then only two types of fabrics: woolen ones, and linen. (Only the very rich, on rare, ceremonial occasions, clothed themselves in imported silks.) 

Of the sixty-five distinct sheep breeds in Britain today, the oldest is the Soay, a descendent of the animals brought by the earliest Neolithic immigrants. A remnant population still lives on the St Kilda islands off the Outer Hebrides. They are typically brown, black, or cream-coloured, with white bellies, and both ewes and rams have downward curving horns. Their wool is fine and short (2"). 

The tan-faced mountain breeds, still surviving in many variations, descend from medieval stock of marsh and hill sheep. Intelligent and very hardy, the ewes have a keen sense of direction and remember migratory trails from season to season. The mountain breeds generally have a coarse, hairy outer-coat over a fine woolly under-coat. The wool is loosely packed, even stringy in appearance, allowing the sheep to dry out quickly after a sudden downpour or washing. 

The Danes brought over native multi-horned sheep during the Viking invasion, some with as many as six horns. Their descendants are still bred for fleece and flesh in Britain. They found their way into ornamental sheep parks for the gentry in the seventeenth century. 

Interested in sheep and sheep lore? Shire Album #157 British Sheep Breeds by Elizabeth Henson is a marvelous little book. And Dorothy Hartley's Lost Country Life, Pantheon Books, is an exhilarating and inexhaustible mine of information on medieval trades and daily life.