I live next to a park. The back gardens of several properties in a row share a boundary with it. We all have wooden fences around our gardens. From the park you can see that for the older houses the fence is the only thing between the gardens and the park, but that there is a second chain-link fence on the park side of the newer houses' wooden fences.
From the solicitor's reports when we bought the house, I understood that the wooden fence is our boundary. My neighbour thinks the metal fence on the park side of the wooden fence is the boundary - also from solicitor's reports when she bought her house!
How do we find out who owns the strip of land between the two fences?