I know you have stated you have stone walls but to keep these sheep (if you really really want to) are you able to fence other areas? I once had manx x shetlands and several were escape artists! When it came to lambing, the only way to keep the little buggers in was a minimum of 6 strands of electric on double whammy! Even then there was always the same ones looking and wondering if she could get under or over. One in particular thought that she would manage it. Getting feet tangled apparently hurt so she learnt her lesson! Over time though (you will too as you get into more, or you'll end up frazzled!!) you'll come to the conclusion that some aren't worth it! You'll flog it (private or auction) or eat it! I had one particular shetland ewe, she was beautiful and very trying!! Got shot of her after a year or so. When I want the sheep to come to me, they come, not follow that cretin the opposite direction. And I have also come to the conclusion that anyone who thrashes at shearing, departs! Annoys me, never mind the shearer!!