Boundary posts were used by railway companies to mark where their ownership of the land ended, especially when this lay outside of the trackside fences.
This example lies within Wavertree Playground and belonged to the London and North West Railway Company. On the other side of the Railway bridge you can still see the steps which lead up to the now defunct Smithdown Road station. Every so often, vague plans to resurrect some of Liverpool's lost stations are mooted. It would be lovely one day to see this station bought back to life.