]"I wrote to Mr. Wickham, who left the place immediately"

What is the meaning of 'the place'?
Is W living in the same place with Giorgiana, and if so ,why Darcy let him with his sister especially that he knows bad things about him as he tells Lizzy in his letter.

"The vicious propensities -- the want of principle, which he was careful to guard from the knowledge of his best friend, could not escape the observation of a young man of nearly the same age with himself, and who had opportunities of seeing him in unguarded moments,"