Business as usual
Banks do pay huge sums for the services of GCHQ types to make sure they are as secure as possible. And I doubt they will even notice the attempts by the secret squirrel types trying to break in during the war games, mainly because they tend to be constantly under attack for hackers of every level all over the globe. Being high profile and dealing in money makes them obvious targets for hackers, and they are well aware of that. Oddly enough, Microsofts Patch Tuesday and poorly trained operators tend to have a bigger impact on uptime than hackers.