The owner of the land has, in the past, applied for planning permission to build a house which was rejected.
Upon further cursory investigation, it appears the rejection was due to proposals by the Highway Agency to widen an adjoining road which would have meant, I presume, said road would move closer to the boundary of the land in question.
However, the land particulars from the vendor suggest the Highways Agency are no longer planning on widening this road so, potentially, any future building plans should be approved.
With this in mind, the question that arises is why isn't the vendor pursuing obtaining permission again - in theory all he would have to do is update and re-submit his previously rejected plans which, I believe, shouldn't be too costly.