I know there is a badger set in Bromley. The young may have spread this far, but I think it unlikely as they are a social animal, and stick to an area. Also their main food source is earth worms, and i suspect the evidence would be pretty obvious, and word would have got out.
If you are lucky enough to have some near by. Then they are quite partial to peanuts. It may take a while for them to trust your garden but worth the effort. Make sure you put them well away from the house and once the are visiting regularly you can gradually move them closer.
happy badger watching.