Hi, thanks for your question. My name's XXXXX XXXXX I'm going to assist you with it.
Unfortunately these questions are all too frequent and I understand the worry that they can cause. In brief, the law treats the issues of height and overhang quite differently, so I will deal with each separately below.
With regard to height, if the four fast growing tress are coniferous, you could consider making a complaint to your local council. This is because there is legislation (Part VIII of the Anti-Social Behaviour Act 2003) that empowers local authorities to deal with the height of nuisance evergreen hedges. There is a fee for using the local authorities' process; the average fee being around £350. The local authority will independently review the situation and they have powers to require an owner to cut trees down to 2m but you must first exhaust all reasonable avenues of attempting to reach agreement with your neighbour first. Failing to comply with an order can land your owner with a fine of £1,000.
The legislation regarding height above does not apply to deciduous trees or single trees that do not comprise a hedge. So, if the neighbour will not reduce the height (or remove) the eucalyptus, then you may need to consider going to court to get an injunction to compel him to do so. However, there is no general right to light in England and Wales. Generally, the rule of thumb is that you would have to show that your light has been reduced by 50%. This is a high threshold.
Your neighbour is broadly correct with regard to overhanging branches and if any branches and roots (from any kind of vegetation) grow over the boundary and into your property, this will constitute a nuisance and trespass. These can be cut off to the boundary line but, once cut, the cuttings belong to the owner (and must be offered back to him before being destroyed).
With that in mind, if all neighbourly attempts have been exhausted, you could consider instructing a solicitor to write to your neighbour advising him that you will apply to the council under the relevant legislation for the height of the evergreen hedge to be reduced and that you will also seek to recover the costs of this application from him in the small claims court. You could also advise him that you will give consideration to making application for an injunction to reduce the height of the deciduous eucalyptus, along with the court costs of doing so. This may get the reaction from him that you are looking for (but neighbourly disputes are notriously hard to predict).
Before you do this, you may try and explain your options to him in negotiation but this will depend on your relationship with the neighbour.
Here is some further guidance on the hedge height rules (ignore the location of the council in this link as the rules apply nationwide): http://www.richmond.gov.uk/home/environment/planning/high_hedges/high_hedges_frequently_asked_questions.htm
Does that answer your question?
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