Thanks for those links. I think in the Pentlands they got the idea from N.Ireland, so it does seem to be being used successfully around the place. It's interesting that in boggy areas the fleece never rots. For potholes in a driveway for example, I think the fleece would gradually rot.
I love the fact that in Cumbria they have used this method on quite long stretches of path, and that they have used Herdwick fleece, wonderfully tough, local and free! The Pentlands section looks to be about 4 feet long. Still, I suppose it's a first trial here.