Thanks everyone - I found out that it was us, because of the recent EE being offline (for some strange reason) it un-installed Firefox's adblocker.
So we installed the "ad blocker ultimate" and turns out that it stops you viewing images such as the banners on websites as well as advert's?!! Reason is that some of the images file extensions could be .ad which they would class as an advert despite it being a picture.
Now I have added on a different ad blocker and we have the banner back!
Not forgetting Monty ✶ Pippin ✶ Alfie ✶ Barney ✶ Sir Wiggy ✶ Kipling ✶ Marley
Glad you solved it Sam. If you need a good blocker in the future try Ghostery. I know it runs with firefox because I use it. It stops much more than ads, such as trackers that tracke your browsing habits. It is fully customiseable as well.