A better way of effecting change
Rather than suing BA for about 1/3 of last year's profit, something that will be regarded as a business cost and forgotten in a few years -- the individuals responsible for failing to ensure secure systems (eg BA board & top level Web managers) should be fined; something like 80% of their assets (ie house) and their pension pot. This will be noticed by directors, etc, in other companies who will then ensure that the same thing cannot happen to them.
I assume that customers who suffered losses will have those repaid by BA; something for the inconvenience would also be good.