Wonder whether it ever was a bandstand for it is hardly raised to give onlookers a good view, nor does there seem to be a dish shaped area for them to assemble . The closed sides and the fixed bench seats inside and outside seem to make it a purpose built shelter against the elements rather than a place for public performances that has been converted.
However, as you suggest, it is rather ornate for that purpose and I am reminded that there were occasions in Brighton at least, where buildings of style and character actually concealed an entrance to facilities like sewerage services. For example, I have an illustration that shows a mock up house at the top of the cliffs in Telescombe hides the entrance to the sewerage outfall that goes out to sea beneath it.
By the way, in case you had not picked it up, the item they are all sitting on is a children's see-saw (note the unusual seat giving access from both right and left). So wherever it was, it was near a play area and the council could afford quality equipment.
Roy G