Thanks so much to everyone who has responded.
Mine is a very informal arrangement to be honest, we've agreed to reassess things at Christmas, but we've shared now since early September and I have no problems at all, some days I hardly know she's here, but other days, we potter around quite companionably, and believe me, this is a very small cottage!
If things were to change obviously I'd have a chat and try to resolve any issues, and it would be only fair to ask if I'm doing anything that irritates her.
I think you can get the measure of people quite soon, and anyone thinking about it should have a good long chat with the proposed housemate first, find out about their lifestyle, likes and dislikes etc.
But I'm talking about 'mature' sharing, which hopefully lessens the risks somewhat.
I think this would appeal to people who maybe find themselves living alone more thro circumstance, rather than choice, and hate the empty silence.
I think, carefully handled this could be the answer for so many 'mature' people.
Lovely to read so many thoughts. Thank you.