I remember those odd possible GEC lanterns from when I was there, I also took photos of the heritage lanterns from the city walls.... near the racecourse there is an Iridium mounted on a very very short column.I walked past the racecourse but I didn't see the short mounted Iridium.
If you walked the full length of the walls, did you spot the sliced 2000? It's on the canal pathway below the walls as it goes round a corner, no streetview image but it's roughly in this area (other side of canal to SV car).I walked most of it as I started where the heritage clock thing is then went in an anticlockwise direction. Tried looking for any oddities, couldn't find the sliced WTRL 2000 but I did find a smashed four windowed, one piece bowl lantern as shown in one of the links that I have provide don the previous page on the opposite side of the road from the possible GEC lanterns.
I'm planning on visiting Chester again sometime soon, so I might be able to find a few more hidden lanterns.