I apologise for the delay in reverting to you. thank you for the above information. Unless your deeds contain restriction restricting your rights to light over the neighbouring lands, from what you say, your property will have the required is nothing else, prescriptive rights to light over theland by virtue of long use.
accordingly, your neighbour placing objects of any kind front of your windows so as to block or substantially restrict the light you enjoy through those windows may amount to an unlawful interference with your right to light. To succeed in an action for interference with a right to light it is not enough to show that the light enjoyed is less than it was before. You must show that the reduction in the light enjoyed amounts to a nuisance. Nuisance arises if there has been: "as a matter of common sense, such a deprivation of light as to render the occupation of the [dominant land] uncomfortable in accordance with the ordinary ideas of mankind." (Colls v Home and Colonial Stores  AC 179).
essentially what this means, is if you can demonstrate the light being blocked is quite significant you may have a claim for a nuisance and unlawful intererence with your right to light and seek injunctive relief requiring her to remove the items at least sufficiently so as to allow sufficient light through your windows. To seek an injunction in this respect you would need to complete form N16A and have evidence both of the interference in question, a report from a specialist surveyor to confirm the reduction in light if the court requires it and evidence you have asked her to remove the obstacles before issuing proceedings:
in terms of getting access to your neighbours land for the purposes of maintenance, you would need to obtain your neighbours permission this respect. If she is unwilling to give such permission, you would need to consider applying for a court order and the access to neighbouring lands act. The Access to Neighbouring Land Act 1992 enables access to adjoining or adjacent land for the purpose of carrying out 'basic preservation works' to one's own property including maintenance, repair or renewal of a building and a wide range of other works but not for building works. in order to bring an action, you would need to show evidence of what maintenance works you need to carry out, why they are necessary for maintaining your building as oppposed to just desirable and that you have previously requested access informally and been refused and ask the court for an order to allow access in the period you require it. You can make the application using form N244. There is a fee of £255 unfortunately to make the application which you are unlikely to recover from the neighbour.
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