Like all furry inhabitants of the wild, they ARE subject to rabies (yes, yes, I know that rabies is non-existent in the UK). And if you are feeding them you are making them dependent upon human food -- and if they can't get it they'll take it one way or the other. It screws up their digestion and their health, and they "unlearn" how to feed themselves in the wild.

For their sakes, please DO NOT feed wild animals!