I had one last year and was quite frightened. However, I bribed someone to go into the loft and there was no sign of anything..... not one wasp. I was still not happy and removed all christmas decoration boxes so I don't have to venture there again! I did do some research and Robinia is quite right. Apparantly they never return to the same nest although thay MAY set up home right next to the last one but this is rare. So far my wasp spotting activities this year have failed to see any going in the same hole this year. Phew!!!