Problem: 5-year big-bang modernisation programme stalled after 18 months with nothing in production. Restructured around incremental delivery — first production service live in month 4 of the revised programme.
Solution: Deprioritised comprehensive requirements in favour of shipping one product (current accounts) incrementally. Parallel-run strategy: new accounts on new system, existing on old. Month 4: new account openings live. Month 5: transfers. Month 6: direct debit. Old system as fallback throughout. Monthly demonstrated progress replaced annual Gantt reports.
Technology: Parallel-run strategy · API gateway · Go · Postgres
Optimisation pattern: big-bang-to-strangler-fig-incremental-delivery
Outcomes:
First live service: month 4 vs. year 5. Regulator relationship improved. Board confidence measurably higher. Programme cost on track to be 31% lower than original estimate.