Right, so in retrospect: sneaking up hadn't been the best of ideas. "I'm Graham. We're on my property - outskirts of Irvine?" He displayed his hands, palms flat and waist level, because the jump had been a pretty clear indication of fright.
If she were a mugger, she'd chosen a strange way to go about it. Graham was more inclined to believe 'drunk and lost.' Perhaps from the local college?