Well when your choices are here, Prison or the Dursley's this is probably the best option.

"Oh, it wasn't." He admits. "On purpose, I mean. I just.. got really angry and it sort of... happened." His story is a little vague but he's still not too sure if it's safe to tell people about magic. Or how they'll take it. She mentions where she's from and he jumps on the option to change the subject.

"Oh! I'm from Surrey-in England."