The challenge
The bank's core infrastructure had grown over a decade into a estate that was expensive to run and slow to change — while the regulator's expectations and the bank's own digital roadmap kept rising. Leadership wanted the economics and agility of cloud, but with a constraint that was not negotiable: customers could not experience a second of visible interruption, and every step had to stand up to audit.
Our approach
We began with a workload-by-workload assessment rather than a wholesale lift: each system received a disposition — rehost, re-platform, re-architect, or retire — with its own business case, dependency map, and rollback plan. Compliance requirements were designed in from the start, with data-residency, encryption, and audit-evidence baked into the landing zone before anything moved.
Migration ran in rehearsed waves. Every cutover was executed first in a staging environment against production-shaped data, timed, and only promoted when the rehearsal met its thresholds. Rollback was a tested procedure, not a hope. In parallel, a FinOps baseline was established so cost visibility arrived with the workloads — not as an afterthought.
The results
The programme completed three months ahead of schedule with zero seconds of customer-facing downtime across all cutovers. Post-migration optimisation — rightsizing, storage tiering, and workload scheduling — reduced cloud spend by forty percent against the initial run-rate, and the bank's teams now release infrastructure changes in days rather than quarters.
Client name withheld. Engagement details shared with permission.
