There’s a central pillar in the driveway between my house and next door’s, and our garden gates hang from each side of it. Both houses were built at the same time. Which of us is likely to own the pillar, or is it likely to be jointly owned?
I suggest you look in your title deeds, which will probably say that the pillar is jointly owned if they say anything at all. If there’s a wall or a fence running back from the pillar you should get some idea of where the boundary runs – assuming you know who owns the wall or fence! The title deeds may show “T” marks, with the leg of the “T” pointing towards the owner of the fence; alternatively the fence posts or wall supports are usually (but not always!) on the side of the fence owner.