My late father-in-law was given permission to build a house on greenbelt land. However the property was built with an additional basement that was not approved. My mother-in-law wants to move house, and would like to get retrospective planning permission for the room, but is not sure whether it would be approved. What are her options?
You should probably take advice from a surveyor or architect with detailed knowledge of the planning laws. Generally speaking the local authority cannot take enforcement action over this type of breach after four years, so (assuming the basement has been there longer) it’s unlikely that a surveyor acting for a potential buyer would query permission for the basement. However local authorities do have powers to deal with concealed breaches. You could start by having an informal discussion with your local planning department about this.