Having worked in IT for over ten years, but never for one of the big banks, I tend to think of banks as the exemplary institutions that spend huge amounts of money and do everything right. This just goes to show, even banks can get their IT horribly wrong.
Letting one power failure knock out so many different systems like this should simply never happen, this is the kind of thing that IT engineers spend all day every day working to prevent. Why were there no backup power supplies, why was there no standby site, why were all the branch systems, cash point systems, and online systems dependant on this one single point of failure in the first place. This is a shockingly bad IT cockup.