I actually read this sometime over the last 3 months I think. Similar to the Lucky Jim stories.
Guy inherits a property, and finds entrance to hidden basement uner the stairs. There was some work with ground radar to find water and a tunnel was dug for wind turbines. I house was built on the other side of a mountain (I think) which some family moved into - They find guns, jewels and old coins in the basement.
Help put me out of my misery please guys!
P.S. I seem to recall something about a furniture store with a closed off storage area with some antique furniture in it - But that may have been a different story