I'd wager there was a solid amount of general incompetence involved at the PO "corporate" - management politically couldn't admit that their consultingware could be anything other than perfect, because they signed off on the decision to buy it, and probably on all the work orders that got them to that point.
If anyone from PO management or that of the consulting firm (Fujitsu, I believe?) ever get any work again, it will be a travesty of justice.
She has since been thrown under the bus, though, of course, not prosecuted or imprisoned (despite ordering wrongful prosecutions of over 900 others)
The politician responsible for her was Vince Cable, who since became leader of the Liberal Democrats, and holds 10 positions, most of which are either funded by the government or related to it.
But when the ball started rolling, as the software rolled out and was finding missing funds everywhere, you'd think a normal person would have asked "are we sure there are no bugs here?" That was never done, I believe, because the software was matching the leadership's priors.
That has to be the most egregious confirmation bias I've heard about.