A couple of re-thinks and a duck.

I've been thinking about my post on the eleventh, especially about the horse tunnel. A more careful examination today, it wasn't raining, revealed

this roller. Simple, you set the horse off down the tunnel and once the boat is moving you drop the rope off the looby and out she comes under her own inertia. Alternatively you could just lift a top paddle and flush her out.
As for the odd arched stone

at lock thirty-three I'm now wondering if perhaps it was just a stone from the original staircase that had just been re-used at some time.

Here's one for the ornithologists, mandarin or wood duck?

Watch this space...............