A small bunch of them came buzzing round the eaves the day before yesterday; these, I suppose were the scouts.
And then yesterday I was sitting out on the patio, reading a book, when I heard a droning noise. I looked up and the air was full of them. Thousands of them. I decided I'd be better off watching developments from inside.
They were settling on the side wall, just under the guttering. There's a hole there- leading, I think, to the space between the wall and the tile cladding- and they were queuing up in orderly fashion to go inside.
This morning they seem to have settled in nicely. They have a few sentries posted and the workers are coming and going.