To see how much the level has dropped I happened to take a "before" photo of the twin culverts opposite us earlier in the day. Compare it to the "after" photo I took before going to investigate the leakage.
The route took us across an old bridge across the now non-existent Great Central Railway. You might just be able to make out the spire of Braunston Church on the horizon on the left.
Tomorrow we will have to decide which way to go. North Oxford or Warwick and Napton. We've sort of decided to do the Shroppie; it's just a question of which way.