Behind the fuel tank is a fibreglass shield which just acts as a bit of extra protection from stuff on the engine side, and is also a bit of a vanity panel. Mine was looking OK but it seemed foolish not to remove and repaint it since it was easily accessible. There are three fixings to remove:

Centre fixing:

Left hand fixing:

Right hand fixing:

Once removed, you can see that the fuel tank itself is directly behind this shield:

I don't have any photos of the repaint process but to be honest there was nothing to see anyway. I just masked off the aluminium bits so that they didn't get covered in paint, then sprayed it with silver Hammerite. Here it is installed in its rightful place: