This happened to us, and i'm CONVINCED it was our boy that went telling all the local cats that our house is the place to be. We now have three cats, our original boy, his girlfriend who he brought home one night and she never left (turns out she was a neighbours cat who had never settled and they were happy for us to adopt her) and now a very old lady cat who belongs to someone on the road, but since they got dogs, she has been living outside (apparently for 4 years according to some neighbours) and she's decided to move herself in, which her original owners don't seem to mind.
Weirdly, they all seem to get on. The old lady cat keeps herself to herself and sleeps the days away whilst the other two are always off together having adventures. I just hope they don't bring a new friend home! I'm running out of cat food!
I occasionally feed Thomas, the local ginger tom with no fixed abode, have been feeding him for 10 years on and off. He sometimes disappears for weeks.
Thomas has now started letting him self in through my bedroom window. He is told to go out and heads for the back door.
The cat from next door, Tiggy, has tried to come into my front bedroom when I am in there (use it as an office/study) so has one of her offspring.
At 1am I was woken by a cat catcalling, another cat, I have only seen this one in the garden a couple of times, must have come through the bedroom window and was yowling at my own cat in the living room.
They are all trying to move in!
Have they sent a memo out that I sleep with a window open?
Thomas is the only one who is fed, and he only gets dried food so it's not like I'm a gourmet cat restaurant.
The cat that woke me was chased out of the garden by my own cat earlier today, but she doesn't seem bothered with cats actually in the house.
BTW I'm in a bungalow so the windows are not high, and it's too hot to sleep with them closed.