Three lots of next door neighbours ago planted an ivy close to our boundary which of course grew up my side of the semi as well. Didn't much mind as it looked quite nice.
Current neighbour recently asked me if I'd mind them pruning it. I replied it was actually theirs, so they didn't have to ask.
With that information, they got a man in who cut it off at the roots and removed it from their side of the wall leaving the bit on mine to die off. (rather like the way some paint a wall with a nice straight line where the boundary is) Which will take some removing and disposing of.
What's the legal position? Only out of interest as I see little of my neighbours but they are pleasant enough.