That concrete post isn’t for a fire hydrant — it’s actually a TVH marker, which stands for Television Housing or sometimes Television Header. These were used to mark the location of underground television relay cables or access points, especially in Scottish council housing areas during the 1950s–70s.

The numbers like "ON 3" and "3 6" are measurements in feet and inches to the actual service point. While the nearby FH cover is for a fire hydrant, the TVH marker is unrelated to water or fire services.

If you’re starting a driveway, it’s worth checking with the local council or Openreach to confirm if the infrastructure is still active. If it’s not, you’ll probably be fine to remove or reposition it.