OK here's the latest:
Wheelers in Chipping Norton took a good look at the car adn as I suspected could not find a fault
However this morning, the battery did struggle to light the engine, and I duly mentioned this. I do know that an iffy battery can produce some spurious codes in some cars, but I would be surprised if it would cause some sort of surge and knock out that fuse (but then Im no electrical engineer and someone may think differently on that one)
So, in conclusion to todays investigations, the bad news is that nothing was found. The good news is that I have a new battery!
I think I'll take the car over to Oxford SAAB and ask if they could check for any codes that might show on a Tech-II and not on a generic code reader that might point to something.