Is there a legal height for hedges?
In respect to this, is there a legal height for leylandii hedge?
Dont grow a Leylandii hedge to a height that will affect the reasonable enjoyment of their property. This includes cutting out light or blocking a cherished view. Remember that keeping a hedge below 2-3 metres means it is much easier to trim.
Moreover, can I reduce the height of my Neighbour's hedge?
You are allowed, by law, to prune the roots or branches of a hedge if it's a nuisance and protruding into your garden. Your local authority can order the reduction in height of hedges, especially if light is being blocked to you or your neighbour's house and/or garden.
A high hedge is defined as a line of trees comprising at least two evergreen or semi-evergreen trees or shrubs and a hedge height of more than two metres above ground level. Local councils will charge a fee, and some may be reluctant to take action, but ant-social legislation is a potentially useful remedy.