A swarm of honey bees entered and dived deep down into our chimney, and dozens also started coming in our windows earlier today. The very last thing we wanted was to have to have the swarm exterminated (given its awkward, relatively inaccessible location), so followed Rob’s suggestion and lit the wood pellet burner - to 30C… Within a few hours they’d gone elsewhere… hopefully.
This was extremely helpful guidance - thank you @Rob_le_Pest for posting this (in an old, 2017 thread)
Since I last posted about this problem back in 2017 we’ve had them return twice more. They always manage to get into the cupboard upstairs which houses the water tank. Now, all we do is block all exits from the cupboard and they generally leave in a few days. No bees harmed!
Since we’ve had bees in several chimneys along the street… folk tend to burn a little cardboard in the grate… at this time of year… makes smoke up the chimney without much heat and acts as a deterrent…
Reading with interest as last year I had hornets starting to build a nest behind one of my wooden shutters. I caught it in time before it became too large, but they persisted in trying to build a nest in the same location. Does anyone know of anything I can do to deter them from trying again this year???
Good question, no specific answer; I’ll read my grandma’s compendium 
You can’t use insecticide as a prevention, but maybe scrape all previous residue of nest and maybe clean with a ‘pine-fresh’ disinfectant. I genuinely don’t know.
Wasp or hornet traps are useful. I use ‘only beer’ as a lure no syrup, vinegar, wine etc. The yeast attracts hornets but repulses bees. Again, you can speak with 50 grandmothers and they will give you 50 different answers! 
Love’em 
Thanks Rob, useful to know.
When we had someone take away our bees nest in the water meter hole in the ground (great shame, they were very happy there, but the water company insisted) the guy who took them then sprayed turps (I think) in/around the hole to stop any future generation of bees from coming back.