Some very amusing posts - I love this one...
The matter was resolved when one of the sons of the house, a young man in his late teens like my mother, announced:
"You're sitting on the chair I put my clothes on when I go to bed."
That's a corker
!
But seriously; I don't know quite what the protocol is for an evening visit - or any other time of day visit come to that, but my intuition tells me that if someone asks me round for coffee / drink / chat, after a couple of hours max, it would be time to make a move. Any longer and I would feel that I was outstaying my welcome.
However, as others have noted, some people are a bit thick-skinned, or just don't want to leave the warm glow of your hospitality (which is maybe rather sad) so I think with such people you just have to be politely honest and tell them that you have things to do / or are tired and need to go to bed, depending on the time of the visit.
My pet peeve is people who drop in unannounced - not those that come for 10 minutes, but those that are 'dropping by' and intend to stay for a couple of hours. I just sit seething and annoyed with myself that I didn't have the guts to say something like "now is not a good time". Like many, I suspect, I plan my day and as the sole carer of a disabled partner with whom I run a small consultancy agency, it's usually a pretty busy day and I just don't have hours to spare. Unless it's an emergency.