Well it is how it is and I am afraid that's that. Anyone following this whole thread will understand why it ended up with the shelves and I am sure would have done the same.
As a recap, two sides have existing foundations for the existing wall and cutting back these footings and underpinning with new brickwork with no overlap would have weakened it to the point I wouldn't have slept at night. I accepted shelves here from the start.
The shelves on the back walls came about due to the great collapse due to torrential rain. This was after the slab had been poured. We had to dig it all out into an extra skip and decided that whilst not ideal we would rather have the extra gallons and surface area than buy tons of soil to backfill it all with.
Anyway, it wasn't planned this way but circumstances have left us with what you see and we are very happy
Sometimes things just happen and we don't all have a blank flat bit of land to start with.
I too cant see any problem with Ted's pond as i very much doubt the fish will try to flash on the sloping part just the flat wall and i think we all know if there going to do it its usually on the bottom drain 
