What is the current legislation about leylandii & other high hedges?

Leylandii can still be planted as a hedge without any problems as long as they are well-maintained. The Anti-Social Behaviour Act 2003 relates to high hedges and allows councils to take action where "reasonable enjoyment of a property is being adversely affected by the height of a high hedge situated on land owned or occupied by another person". Nuisance hedges (not always leylandii) are often planted deliberately to annoy neighbours. Hedges should be kept to a height where they are not a nuisance to neighbours. There are complicated calculations to determine what constitutes a nuisance hedge that take into account factors such as proximity to a neighbours house, height of hedge and the loss of light to a house or garden. If you are planting a hedge close to a neighbour's house you must not let it grow more than 2 metres (6'6") tall.  more