Modernising critical legacy systems without disrupting services — The National Archives
- The National Archives wanted to modernise its critical legacy system to make it more resilient and better handle the growing volumes of records.
- Zaizi proposed a phased “transitional architecture” approach to replace the system incrementally without disrupting services, rather than a high-risk full overhaul.
- The project delivered a clear roadmap, prioritised actions, and validated insights — enabling the organisation to build a strong business case and modernise sustainably.
Customer overview

The National Archives is responsible for preserving and providing access to government records, including documents over 1,000 years old, such as the Doomsday Book. As a custodian of national history, it manages growing volumes of information while maintaining critical public services.
The challenge
“We had to get a good analysis of what we had and to work out how we can replace those in chunks. That meant we could continue to deliver service and not have a period where we had nothing.”
Dr Chris Owen — IT operations, The National Archives
Many public sector organisations run legacy systems because replacing them is a balancing act between security, value for money, and service continuity. But these systems pose increasing risks; for example, unsupported components, cybersecurity vulnerabilities, poor usability, and the inability to handle the increasing volume of data.
The National Archives wanted to get ahead of these potential issues and update one of its critical services. As with any legacy system, large-scale replacements can be complex and difficult to deliver without disruption.
So, The National Archive approached Zaizi to investigate a pragmatic way to update its system while maintaining essential services.
The approach
“We were very pleased with the people who came to work with us. We found that they understood their specialities, particularly on the technical front. They were straightforward and good in their dealings with people at all levels of the organisation who use the services.”
Dr Chris Owen — IT operations, The National Archives
We worked on a rapid six-week discovery, collaborating closely with the client’s IT team and stakeholders. We mapped processes, clarified problems and requirements, defined user needs, and assessed the technical landscape.
Instead of a high-risk “big bang” replacement, we suggested a transitional architecture that incrementally replaces the legacy system. It means the system will remain operational while we gradually improve resilience, usability, and maintainability.
Our approach emphasised practical, achievable steps and challenged existing assumptions while acknowledging organisational constraints.
The outcome
“The value’s been finding the key things that will make a difference. We had some understanding of that but the Zaizi team helped us put that in sharp focus. They identified the key pain points and suggested some useful strategies to keep the services running smoothly.”
Dr Chris Owen — IT operations, The National Archives
The National Archives already understood the issues. Our work provided an outside perspective, helped align stakeholders and provided the roadmap to modernise.
Key outputs included:
- stakeholder mapping
- user needs analysis
- process and workflow mapping
- prioritised technical recommendations and roadmap
As a result of our work, The National Archives had the insight and supporting materials to create a strong business case and modernise its systems in manageable chunks while continuing to deliver its services.
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