No Rear Coal - Problem or ornamental?

I recently called out British Gas to service my Robinson Willey Firedance gas fire. They found that the rear coal was missing and therefore have left the gas disconnected. I cannot believe that this is dangerous? I would think that the rear coal is merely ornamental. The rear coal (ROBIN WILLEY SP992232 COAL REAR) is no longer available as a spare which means that I would need to replace the entire fireplace. Any advice would be appreciated.