Problem solved!

So the solution to this rendering problem was so blindingly simple I'm still kicking myself. Rob helpfully pointed out that if the rendering works through the perspective camera but no others, why not just animate the perspective camera? Im such a foool!! Of course I would have liked to have understood exactly why it didn't want to work through any new cameras, but with the time we have left I think it's best to just leave it be for now.

Here's a quick playblast of the updated camera movements. It means we get a better view of the statues out front now, which is good.

On a completely seperate note, Dan pointed out that I didn't have a folder with my textures in, and in fact the location of my bump map texture was set to the public folders. This was going to cause problems later on, so I had to save the texture into a newly created texture file and reload the location of the file in the scene. I also finally got round to deleting loads of old files, opening up so much more space for saving and generally keeping my project folders tidy.

Next steps are to get the image plane up for the background, maybe do some soft modification on the ground, and try and apply a bump map to the path. Other than that it's nearly render time!