The challenge
The bank’s starting position in 2022 is the one most large SharePoint estates reach eventually: a fragmented environment of legacy farms and virtual servers, upgrade and continuity costs that had stopped being justifiable, and the compliance exposure that comes from how many vulnerabilities such an estate accumulates.
None of that is fixed by migrating alone, because migrating takes years and the estate has to stay secure and available throughout. The bank could not treat the legacy platform as already gone, and could not stop either, since each year on the old footprint costs another year of the same.
A second constraint shaped the opening. The work began by replacing an incumbent vendor, and a programme that starts with a handover has to establish operational credibility before it earns permission to change anything.
The solution
Two tracks ran in parallel, and the defensive one came first. Track one hardened the on-premises environment, took over incident management and disaster recovery, and guaranteed continuity. Track two migrated and modernised. Running only the second is the common failure: it produces a modern target and a decaying source that still carries the business.
Migration was sequenced from volume to complexity. The site numbers tell the story better than any total:
| Year | Tier | Sites migrated |
|---|---|---|
| 2022 | High volume | 4,860 |
| 2023 | Complex | 1,277 |
| 2024 | Highly complex | 429 |
| 2025 | Very complex | 57 |
The count falls by two orders of magnitude while the difficulty rises, the opposite of how migration progress is usually reported. Front-loading the straightforward sites clears the estate quickly and leaves a shrinking population of hard cases to handle individually. Alongside them, 1,500 legal-hold sites moved with full historical fidelity and metadata preserved, a category where "mostly migrated" is not a status anyone accepts.
Customisations were refactored, not carried across. Roughly 1,200 Infowise and InfoPath forms became Power Apps, because an Infowise form is a configured add-in rather than a document and nothing lifts it. About 2,000 SharePoint 2010 and 2013 workflows moved to Power Automate and Nintex Cloud. Reporting left SSRS in SharePoint Mode for SSRS Native, Power BI and SharePoint Online, taking 100+ bots and 200 Tableau reports with it.
Tooling was industrialised. Sharegate, Content Matrix, the SharePoint Migration Tool and File Share Migration Manager did the moving, wrapped in 100+ custom scripts for orchestration and 200+ more for monitoring, disaster recovery and patching.
What could not move yet was kept working rather than forced. 24 business applications remain in hybrid mode through on-premises data gateways. Naming them as a hybrid population, rather than migration failures, is what lets the decommissioning plan carry a date.
The results
By December 2025 the migration stood at 99.9% complete, and the support function taken over from the incumbent was answering in as little as nine seconds. The remaining work is scheduled rather than open-ended: 114 business applications and the last five complex sites through 2026, farm count down to four, server footprint under eighty, and full decommissioning in June 2027.
What changed is what the bank’s teams can assume. A platform that was a compliance liability and an unbounded cost became one where a change window is ten minutes, everyday forms and workflows run on a supported platform, and the end of the legacy estate is a date rather than an aspiration.