There's an unpleasant spirit evinced in a number of the replies in this thread. First people start suggesting that the neighbour lied about being stung, despite there being no such suggestion in the original post. Then the neighbour is attacked for for doing something perfectly reasonable in his own garden. The problem that subsequently arose was something that neither of the parties could foresee.
Next people are trying to find ways of deliberately making the neighbour uncomfortable, for example by planting leylandii, despite the fact that the beek says he can get round the problem.
The original poster simply asked if anyone had any ideas about why his bees disliked his neighbour. He didn't say that he had a problem with him or that the neighbour was in any way dishonest or unreasonable. The info about the raised garden came later, and there's no talk of a falling out between them, just an objection to the planning application, which is nothing unusual between neighbours.
Too many people who come on this forum are just plain petty.