I wrap the compost bins here with several layers of chicken wire which has helped. Before I knew there where rats around I found a nest in one bin that was full and left for a few weeks to do its stuff. I was turning the contents and suddenly there were baby rats running everywhere. The dog thought it was christmas. Now I keep them wrapped up tight. The garden waste only bins are just open pallet types and I get all sorts in there. Snakes, slow worms, nesting bees and god only knows what else. As long as it isnt rats I dont mind.
Pretty much my take on it Dave.
I have the big black dalek style bins though. No idea how to use the chicken wire on them. We did set them onto solid 3 x 2 paving slabs though to stop them tunneling in from underneath, so I just don't know how the blighters are managing to get in. I think we need to look again at the base and the exit port.
M