Thanks everybody, I have to admit that I did actually kick him when he bit me, intstant reaction, it bloody hurt! They are built so solidly though (and I far from it), that I can't imagine it hurt him one bit. I read elsewhere that you should rap them on the snout with a stick, so I think I shall give that a go. Though they seem completely unphased by everything, even the neighbours dogs barking in their faces. They were much better behaved this evening, no biting at all, so hopefully things will improve quickly.