In Northanger Abbey, Chapter 11, Catherine Morland has agreed to go walking with the Tilneys at 12:00. But when the scheduled time arrives, it's raining, making the walk impossible. At 12:20, Catherine says "I shall give it up entirely." At 12:30, though, the rain starts letting up, and by 12:40, it's definitely clearing. But Catherine is unsure whether she "might still expect her friends." Then the Thorpes and James arrive, and by 1:00 Catherine has been convinced to give up on the Tilneys in favor of a trip to Blaize Castle. "A few minutes after [their] setting off," the Tilneys do come to call on Catherine. When Catherine finds out that she just missed the Tilneys, she feels obligated to explain herself to Miss Tilney, at least: "I shall not be easy till I have explained everything."

I realize that we live in a more time-conscious society today, and that perhaps Catherine's anxiety to clear herself with Miss Tilney had more to do with her desire to be on good terms with Miss Tilney and her brother, but I would think that Catherine should feel no guilt for giving up on an appointment after an hour's wait, without hearing any word from the Tilneys. She herself was inclined to give up at the 20-minute mark. On the other hand, there's no indication that the Tilneys were at all uneasy about showing up over an hour late.

So I'd like to know what the etiquette was back in the late 18th/early 19th century. What level of punctuality was expected? How late was too late for a meeting of this type?