Re: So whose bright idea was it in the first place?
I believe the original spec was to do a fairly vanilla installation with minimal customisation, and all departments would adjust their business practices to suit the new software. They'd apparently been using a highly customised SAP product before, but I think there are rules whereby you have to review and compare to the rest of the market occasionally - and evidently Oracle wowed the decision makers.
Of course, with big projects like this, Oracle don't directly get their hands dirty, but rely on third party "Implementation partners" to do the installation and configuration. Chances are they're more used to businesses rather than councils, who have a myriad of different budgets, income sources and expenditures; while of course each department would likely have vigorously protested at having to change their business practices, demanding something that works exactly like SAP. ICT presumably didn't have the authority to resist...
Added onto which, they apparently changed implementation partners part way through the project, which is very telling on itself...