There was a breed of sheep in East Anglia before the agricultural
improvements of the 19th century that was much more goatlike. It was said
they were long legged and rangy, and could jump a 2m fence. Such sheep
rapidly went out of fashion with the enclosure of fields, as they could not
be kept in one farmer's field. Not sure how far back the breed goes though.
Check out the West Stow, Suffolk report for info on Saxon sheep and cattle