Oh Grate

There were a couple of mysteries awaiting for us in the proposed Michaelmas Daisy bed. Both turned out to be air vents; this one almost entirely buried; the other blocked.

We planned to build a brick surround to protect it from getting buried again. With some excavation, discovered it previously had such a protective collar, which had been largely removed.  The recurrent phrase 'why do people do that?' came to mind.