"Although Brandon may've was quiet, he was probably glad to accept invitations to Barton Park for company and found himself well received."

Yes, whatever we may think of the contrast of temperaments between Sir John and the Colonel, an evening at Barton Park for company would almost certainly be more pleasant than solitary dinner at Delaford. Also, it's generally hard not to like those who like us! Granted, Sir John is willing to like almost the entire world unless he has good reason not to (and sometimes not even then, as we'll see), but it must be pleasant to Brandon to go where he's assured of a warm greeting by people who think well of him.