Just read in the latest edition of "Pest" (if you don't get it - go to www.pestmagazine.co.uk - its FREE)
About a wasp nest removal man being convicted of manslaughter in Switzerland!!
While dealing with a nest and trying to remove off a friends balcony, wasps attacked an elderly couple on another balcony resulting in the husband dying from anaphylattic shock 2 days later.
So I guess, the morale is always informing neighbours of your intent. and if treating a nest near a pavement/walkway then do late in evening and then cordon off, As soon as a pestie either dusts/sprays/removes they are liable