OK the boffins have replied and the answer to the Batt fault (everyone remember that?) is
If you have an ELEC BATT fault, you can lose the ELAC roll channel and the SEC’s take over. Roll is now controlled by the spoilers, increasing drag, increasing fuel consumption.
Apparently it is for all S/Ns.
That's all there is to it. Simple isn't it..
Now I have to go lie down for a while.