Most of the banks run on systems build in the 70s-80s. They keep patching them up, tweaking here and there, instead of doing the right thing: create a totally new architecture from scratch, test and dry run it, and then switch the “rails” overnight (some banks did just that, though not in the UK).
The reason for such “coward” behaviour is clear: nobody was fired from the bank’s IT department for spending N on some improvement, but to take on a risk of running (let alone suggesting!) a project that costs N x 10-100, you need two things.
And that concerns not just the banks.
Read more at Finextra