In reply to Adam Perrett:
Each photo has the route name under it so you can just click on that. Occasionally there isn't a route name. This occurs when people upload the photo without choosing the route name during the upload in the 'route name' field.
These orphaned photos can still usually be found when viewing a route but it is a bit of a hack process that searches the assigned crag, and photo caption text, to see if it can find a route. This gives false positives quite a lot of the time. e.g.. "the crack left of Right Unconquerable' will probably appear on Right Unconquerable, not Left.
Reversing this process from the photo to the route is trickier so we don't attempt to do it. We probably could but it would be better to assign route names to photos rather than introduce hack processes. The hack process above dates from over 10 years ago and should be removed. That would of course mean that the orphaned photos didn't appear next to the route they refer to and there are a lot of them so it would be a shame.
Alan