He's so comfortable just chatting away without a proper introduction. While this is completely new for Elizabeth, she isn't one to freeze up in a new situation. Instead she reacts and acts in stride.
"Typically at least once a fortnight, though it naturally changes around holidays."
She pauses there, glancing at him a moment before she adds, "I do not think I have seen you here before, sir. You are new to the area perhaps?" An eccentric rich fellow who's taken a country home here for a bit? She may have to start wondering over Hertfordshire's ability to attract rich men at this point.