I just typed a long reply, then it disappeared into cyber space !!!
The two have separate registers, I'm not sure if others cross breed them, but the lambs couldn't be pedigree registered. I only have Torddu, but would love to have a small flock of Torwens if I had more time. Torddu means 'black belly' and torwen means 'white belly'. They are lovely sheep, the ewes are wonderful mothers and the lambs are born with real get up and go, plus their meat tastes beautiful with or without mint sauce
Wiggy, who had the single is one of my oldest ewes at 9, this will be her last lamb though and along with a couple of others will have a well deserved retirement as paddock cleaner.