Anyone for Tennis?

There's an area of the garden that was (laughably, at the time we moved in) called 'the tennis court'.  Having now cleared a million cubic metres of buddleia, laurel and bramble it is, almost, feasibly tennis-court-sized.

Indeed, fitted on one side about half way along is this curious trip hazard, whose alignment suggests a net post holder.  I was reminded of it as I tripped over it again today while sawing through yet more laurel.

Not yet tripped over anything matching on the other side, but there's time yet.