Thanks. The odd thing is that I looked at the fuse list inside the lid and it doesn't show anything to do with rear lights which seems really odd. I am sure they do have a fuse but I am a little lost as to why they've left it off the list.
Thanks for the diagram, its a little beyond me though!
EDIT: Update: I took the bulbs out of the rear number plate holder and then put in a new fuse. The lights came back on on the dash so I know that its the rear plate lights that are causing the issue.
What exactly am I looking for in terms of a short? I presume bare wires somewhere? The cables going from the body to the boot are all tied together, do I have to undo all of these to check them??