Before I retired I worked for Hewlett Packard as a Solution/System Architect. Involved in many areas including being member of a team investigating New Business Due Dilligence prior to accepting new clients large contracts for IT Outsourcing. Think Inland Revenue, Banks, Building Societies, MOD etc.

Most of the current IT Systems that Banks use are old and creaking and their connections are still not robust or resilient.

Take the latest from Visa......a component failure REALLY. Are they really admitting than their critical services have reliance on one component that is not mirrored with automatic up to date replacement?

TSB had problems when updating an Operating System. This is a normal type of update, carried out by testing on a Model Office (this is a separate non live entity that performs exactly as the live system..allegedly) before going live. When things go wrong on OS updates after testing in MO, the source of the failure can be due to the MO being Live Like but not Like Live.

Security can also be worrisome, software and hardware Firewalls are big issues

I believe in the not to distant future we may see a catastrophic failure of some large utility or corporation.

Sorry for the rant.