traditionally Ouessant sheep were ALL tethered on the island during the agricultural calendar from feb to september. The rest of the year the sheep had and still do free access ( vaine pâturage) to roam the island. The sheep were tethered in pairs.
This text is from writings by Gustave Geffroy on his Impression of Ouessant 1897.
....Et partout, des moutons, des moutons, encore et toujours des moutons, des noirs et des blancs, petits, vifs, attachés deux à deux par une longue corde,........
My translation, "And everywhere, sheep, sheep, more and always sheep, blacks and whites, small, lively, tied two by two by a long cord."