The Ouessant Sheep !
The breed comes from the small island of that name, about 12 miles off the most westerly point of Brittany. These charming little sheep are claimed to be the smallest in the world, with the ram's shoulder height up to 48cm (a little over 18in) and the ewes up to 45cm. Comparable measurements for the smallest British breed, the primitive Soay are 51-61cm for rams and 49-54 for ewes. They very rarely produce twins, and it's unlikely that such a small sheep could carry or raise more than one lamb.
Dr Ryder (Sheep and Man, Duckworth, 1983) concluded that they are related to the northern short-tail sheep breed, because it has quite a short tail and a similar range of colours. The islanders selected black sheep for breeding, for their preferred colour - black clothing was worn by married women in poor rural communities in southern Europe and west of Ireland until at least the early 1900s. A pre-1965 photo of Dr Ryder's book shows a group of Ouessant women, dressed largely in black, taking their sheep on leads to the grazing grounds, where they were tethered.
The horns of the rams are heavy. Curl forward and terminate in sharp, outward turning tips. Ouessant ewes are polled (ie they have no horns).
The exceptionally small size of the Ouessant is attributed to the poor grazing on the island, which led to the selection of small sheep for breeding. The island is composed of the same ancient rock as the Land's End and Lizard peninsulas. Readers might recognise the English name Ushant from the sea shanty Fair Spanish Ladies:
We'll rant and we'll roar like true
We'll rant and we'll roar across the salt seas
Until we strike soundings in the Channel of Old England,
From Ushant to Scilly is 35 leagues.