Different councils have various different attitudes to hedges and how high they should be so it is probably best to make enquiries of your local council. Usually there is not problem with hedges up to 6’6” (2m) tall. However, the Anti-Social Behaviour Act 2003 relates to tall 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”. A calculation sheet has been produced so that you can find out how tall your hedge is allowed to be. You can find the calculation sheet here.