well so much for reporting the problem;
I started with the welsh assembly agri no. as that's the first I found:
They said it was not their dept and passed me onto Animal health.
OK, so I explained to AH about the dumped sheep and their response? "if someone's dumped the sheep on your property then you are responsible for their disposal".
That's it - they aren't going to do anything about it except tell me to pay for the disposal

, so I asked what should be done about stopping future dumping and they suggest I talk to the council officer who deals with fly-tipping.
I guess I'm going to have to solve the problem myself then - maybe you're right Scarlet', I will have a chat with the neighbours, and if they know I suspect them, that's their problem - goodwill be dammed!
I wonder if a sign by the bridge saying cctv in operation would help...