Old NickKilby,
             Your Fly grazing experience presumably took place before the new act came into force,the site below explains the actions which can now be taken to resolve the situation.
The only things a landowner is responsible for is to food and water are available and no harm comes to the animal until the animal is reclaimed by the owner. The horse owner has to refund the cost if they reclaim the horse.


http://www.qualitybailiffs.co.uk/news/articles/fly-grazing-horse.html