Based on the Slaughter and May report into TSB's IT failure which I asusme is "softened" as much as possible, there aren't many parts of the existing UK IT operation that are blame free. i.e. the TSB disaster was caused by mistakes at all levels of IT (and likely the business) and the blame deserves to be shared around.
Having said that, if your internal IT cannot deliver business requirements there is likely a significant disconnect between the business and IT - outsourcing IT will increase that disconnect unless you are completely buying into the outsourcers vision for running your services.
If that's the case, I would expect IBM to advertise for a large number of experienced electroplaters and gold prices to increase as they try to fulfil TSB's IT requirements....