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You are entitled to prune anything on your side of the fence. It appears to me that any new purchaser has no quarrel with you and that you are lucky enough that your intimidating neighbour is leaving. You should ignore her empty threats, you have done nothing wrong, and look forward to neighbour's who are likely to be saner and more rational that her. I hope that helps. Please leave a positive rating so that I am creditd for my time.
That would be very unwise. Do nothing. Let the neighbour move out.
Because she is clearly the type to cause issues. Your new neighbours may not be bothered in the least bit of you start creating issues with the estate agent you might put the sale in jeopardy.
It appears the hedge is on your side.
I suggest you do nothing. Dare I say that if your new neighbors are solicitors they will have more to think about than their garden. Personally I haven't seen mine for months!