This drawing for The Gamekeeper shows there was an intention of having floating game-keeper chairs. In the actual episode all the chairs are on ground level.
This episode was filmed in the Bloedel Conservatory at Queens Park in Vancouver, which is still open today. The Conservatory is home to a range of exotic plants and birds.
I feel bad I just watched this one in the last few months but don't remember this scene, will need to go back and watch it again and look for this.
It's a great episode. If you're ever in Vancouver I highly recommend visiting Queens Park.