This is the view from the North end. The level of water at this end of the path is still too high: that's the course of the path you can see running down the middle of the photo, mind. So I'm going to extend the pond north and south (to the left foreground and middle ground in the photo) once I've got at least some of the path restored, and can start to barrow earth from the East to the West side.
On the plus side, the fact that the path-trench has filled it up with water tells me that it's draining off the West bed, so it's working. It's impossible to say what the levels will be in future, given the exceptional rainfall we've had in December. So it might be a seasonal pond and dry out in summer, or it might be full all year. Whatever. It'll be a pond, and the drainage issue is almost solved.