Delay to European Central Bank messaging project cost the Bank of England £23M

The National Audit Office reports that the Bank of England’s £431m RTGS renewal was largely successful but exceeded contingency by £56m after four replans, including a £23m cost impact from deferring its launch when the ECB delayed its ISO 20022 migration, to avoid excessive change for users. Despite overruns, the NAO deemed the increase reasonable given program complexity and uncertainties; the new system replaces a hard-to-maintain mainframe with an internally hosted, cloud-native platform, delivered with Accenture.