Sam shoves his hands in his pockets, grinning at the look on Cal's face but at the same time keeping an eye on their surroundings - the kid is a very obvious tourist, after all.

A thought strikes him, however, and the grin fades slightly.

"Hey, kiddo, just a thought - if I tell you suddenly to get back to Milliways, don't ask questions, all right? I can't imagine any of my family could possibly turn up, but they've been known to turn up when least possibly wanted before."