@remnet: Yes, in Deathly Hallows chapter 14 Hermoine cast a charm to repel muggles, here's a general description of the spell given in that chapter:
- "Muggle-Repelling Charms on every inch of it. Every time Muggles have got anywhere near here all year, they've suddenly remembered urgent appointments and had to dash away again."
- —Arthur Weasley.
- So they could just win this by doing that.