Whose fence?

Today we escorted our new cats round the garden explaining to them where the edge of the garden is. One side is chicken wire which is reaonably secure. The other side is this old fence . Not cat proof. Mitzi prompty wandered through and said hello to the neighbours.  The other side of their garden is solid wood panels - again secure.  Discussed the old fence with the neighbour, we do not know whose it is.  I guess I had better look at the deeds.
PS no idea what the fungus is but it brightens up the old fence