I agree it is the Vision plus TV aerial mounting pole "steady" clip.
I suspect if there is no lower one, then the base of the pole might simply have sat over a steel rod hammered into the ground.
[I years ago did something similar, using a clip on upper awning rail, base of pole sat on a steel drift. All dumped when we had the directional roof mounted Status aerial]
I would not consider removing it, too high a risk of leaving an unattractive witness mark of some sort, even if only of differing sun fading.