Your solicitor should have found this on the searches. If you believe they were competent, then likely there isn't one. It could have been just a verbal agreement for the neighbour and installer, but it has historic acceptance.
If you have legal protection on your house insurance, you could ask the legal team what your rights are. Chances are, without a legal wayleave, that you may be able to remove it, but that it going to make neighbour relations worse, unless they do not use VM anyway.
If neighbour uses it, see if VM will re-route cable away from your land, maybe public grass verge outside if one exists.