thanks everyone. yes it is the portable soft stuff i am tlaking about, so that is a no-go it seems (as i thought). her field is onto a childrens play park on one side and a factory unit car park on the other so it is important to have robust fencing. she uses plastic posts and electric tape for her horses, which they respect, but i'd be a bit nervous about having just that for the sheep i think. i wouldnt want them (or any people) to get hurt. the 'problem' is that my sheep are really tame and actually seem to LIKE people so i'd be worried that they'd just 'pop out' to visit some humans!
i'm thinking she'll just have to keep him here!