If the work has already been done and completed or will be done and completed by the time the matter exchanges, then I can see no reason why you need to disclose it. If on the other hand the work is to be done after exchange or after completion then it would be disclosed within the Seller’s Property Information Form TA6.
Under the Access to Neighbouring Land Act the neighbour is entitled to whatever access is required over your property to preserve their property and that would probably include this work so if they took you to court they are likely to get the order and they likely to get costs awarded against you.
It’s unlikely however they would get consent within the Act delay a pipe for drainage or whatever, on your land because that’s a completely different issue and the court will not normally force anyone to have an easement.
What you do have here is a potential dispute with the neighbour and that would be disclosable. I would tell your solicitor about this and let him decide. That way, it absolves you. It is more likely than not that you are going to have to disclose this.
I strongly suspect it’s the answer you were expecting albeit not the one you wanted.
Can I clarify anything else for you?
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