downpipe removed by nieghbour

[Guest]

A* portion of my wall at the side of my house faces my neighbours garden, there is a downpipe that runs down that wall to a drain from my guttering above. I recently noticed that the downpipe has been removed completely* from my wall and now have water running out of the gutter on to the wall and the neighbour* back yard were the drian is. Can the neighbour legally do this?*