Case Study — Retail Banking / Digital Transformation
A UK regional bank with around 1.2 million retail customers needed to replace a core banking platform installed in the early 2000s — without interrupting the daily banking that had to keep running underneath the migration.
The Transformation Framework™
The bank's core platform had been patched repeatedly rather than replaced, with critical batch processes fully understood by only two remaining engineers. Prior replacement attempts had stalled once teams confronted the operational risk a live migration would carry.
The real obstacle wasn't the technology choice — it was that no one owned the decision to accept temporary operational risk during migration. Every business unit held informal veto power over changes affecting their numbers, so previous plans were designed to avoid ever triggering that veto, making them undeliverable.
We presented three paths: big-bang cutover, phased migration by product line, and a parallel-run approach with a hard sunset date. The bank chose the phased approach, accepting a longer timeline for the ability to roll back any single product line — and named one executive with authority to approve each phase independent of business-unit sign-off.
Migration proceeded across five phases over 22 months, starting with savings accounts and ending with commercial lending. A dedicated command structure ran daily during each cutover week, with pre-agreed rollback criteria removing the need to renegotiate risk tolerance in real time.
The migration completed eight weeks ahead of the agreed schedule, with zero unplanned customer-facing outages during any cutover window and a 34% reduction in month-end batch processing time.
Measured Outcomes
Reflection
"The migration plan everyone signs off on treats the bank as a system diagram. The one that works treats it as a set of decisions made under deadline pressure."
Sarah Chen — Head of Digital TransformationEngagement team
Founder & Senior Partner
Head of Digital Transformation
Senior Consultant
Senior Consultant