[ In leaving the TARDIS he picks up his staff, the one he made himself at Terre Haute and stands against his hat stand in the console room. Once everyone is out he will lock the TARDIS doors tight.

Eyeing each of the children especially and not happy at their presence but what can he do, lock them in a room? ... That's actually a tempting idea. ]

When you're as tall as I then you can tell me not to go off alone. As for knowing we're here... if the TARDIS didn't alert it, if it has a heightened sense of smell to hunt with that would do it as well. Stay close together. Be cautious.