You can probably get copies of any deeds through the Land Registry Office or certainly through the Sasinines here in Scotland. There is no secrecy regarding them anymore. However, it may not have been the exact Deeds for the house, often a separate set of Deeds stipulated any Covenants, as I currently have on my home. It may be that subsequent development meant that either the Council, or a landowner, often the Church asked for these conditions, many of which were included to prevent the setting up of commercial enterprises in residential areas, and this house was included as part and parcel of the estate. However, when 'J' bought his house his lawyers should have advised him of the existence of any such Covenants which should have arisen while the 'Searches' were being done. If 'J' did not use a lawyer, as can happen in England then it is possible this was not done as estate agents are not so enthusiastically inclined. Again here in Scotland a lawyer must be involved so there is no subsequent dispute.
However, I do not think 'J' has too much to worry about. Even if there is a Covenant then it requires other Parties to bring a civil action, which costs money, and I seriously doubt if enough people would be so inclined.
However as I mentioned earlier the lane is the issue as it is privately owned, not a public highway.