Migrating a legacy system to a modern cloud-based solution

Our consultancy supported a major public sector organisation in transitioning a legacy digital system to a modern, cloud-based solution. The organisation relied on the system to deliver critical services to citizens and internal operational teams. However, the technology had reached a point where maintenance was increasingly costly, resilience was a concern, and the platform limited the organisation’s ability to adapt to changing policy and user needs.

The goal of the engagement was to deliver a safe, secure, and scalable cloud-based platform while ensuring continuity of service. Together with the client’s digital, policy, and operational teams, we shaped and delivered an end-to-end programme of work. This included discovery, technical design, business analysis, delivery management, and support through migration and transition. The project ran for twelve months from initial discovery to full migration, with our team embedded alongside the organisation’s internal specialists throughout.

The scope included understanding the legacy system, defining requirements for the new solution, designing the future architecture, and supporting data migration, testing, and rollout planning. Our approach emphasised partnership, transparency, and sustained knowledge transfer, ensuring the organisation could confidently operate and iterate the service long after the project concluded.

The problem

The legacy system, introduced more than a decade earlier, had become a limiting factor in the organisation’s ability to meet evolving user expectations. Over time, patches and workarounds had made the system increasingly complex to change. Key parts of the technology stack were reaching end-of-life, meaning security updates were diminishing and operational risk was rising.

Operational teams reported frequent downtime and slow response times during peak periods. Policy teams found that making even minor rule changes involved long lead times and expensive development effort. For frontline staff and service users, this meant delays, inconsistent experiences, and the risk of service interruption at moments of high demand.

The challenge was not the result of any single decision but rather the natural accumulation of technical debt, shifting policy landscapes, and resource constraints common across the public sector. The organisation recognised that continuing to invest in the legacy platform would no longer be cost-effective or sustainable. A transition to a cloud-based solution offered the chance to improve reliability, strengthen security, and unlock opportunities for future service improvements. However, the organisation needed to achieve this without disrupting a service used by thousands of staff and citizens daily. Minimising downtime and ensuring a safe migration were therefore central to the problem we were asked to help solve.

“The consultancy team felt like an extension of our own from day one. They embedded themselves seamlessly into our service rhythms and ensured every decision was grounded in how the service actually worked for real users.”

Service Owner

Research and discovery

During discovery, our consultancy worked closely with service owners, technical leads, and operational teams to build a clear understanding of how the legacy system underpinned the wider service. We conducted interviews, shadowed frontline staff, and reviewed operational data to understand pain points and identify what a modern solution needed to support.

This research revealed several important insights. First, many staff had developed local workarounds to compensate for system limitations, and these workarounds had effectively become part of the service. Understanding these hidden processes was essential in shaping the requirements for the new platform. Second, we learned that user needs varied significantly across different groups. While frontline staff prioritised reliability and faster processing times, policy teams needed flexibility to adjust rules and workflows to meet statutory obligations. These perspectives shaped the definition of the new solution and ensured both operational and policy needs were addressed equally.

We also completed a full service map and current-state architecture review, identifying dependencies, data flows, and integration points with other government systems. This work highlighted where risk was concentrated and where migration activities would require careful planning. Bringing all of this together, we produced a set of actionable findings and a roadmap that established a shared understanding of the challenges and opportunities, setting the direction for the design and delivery phases.

“What stood out was how well they listened. They spent time understanding the pressures on frontline staff and worked side-by-side with us during migration. It never felt like an external project — it felt genuinely collaborative.”

Operations Manager

Design approach

Our design approach balanced structured delivery with flexibility, allowing the team to respond to discoveries and emerging risks as the project progressed. We established a multidisciplinary team comprising business analysts, service designers, user researchers, technical architects, and delivery managers. This ensured decisions were informed by both user need and technical feasibility.

We began by defining the core requirements for the cloud-based solution, translating user needs and organisational objectives into clear functional and non-functional requirements. These included performance, security, accessibility, and maintainability expectations. Using agile delivery practices, we worked in iterative cycles to prototype, test, and refine key components of the solution. Close collaboration with the client’s technical team ensured the architecture aligned with existing systems and met government standards for security and data protection.

The team also designed and validated data migration strategies. Given the age and complexity of the legacy system, we conducted several rounds of data quality assessment and mapping to ensure accuracy and continuity. This included working with operational leads to understand how data was used in practice and how it needed to behave in the new environment.

Change management played a central role in our approach. We established clear communication channels, created training materials, and supported internal teams as they adapted to new tools and workflows. Throughout the engagement, we prioritised knowledge transfer so that internal teams could confidently maintain, iterate, and enhance the platform beyond the life of the project. Our aim was not just to deliver a system but to build capability across the organisation.

Outcome and impact

The organisation successfully migrated from the legacy platform to a secure and scalable cloud-based solution. The migration was completed with minimal service disruption, thanks to careful planning, rigorous testing, and close coordination with operational teams.

The new platform delivered a number of measurable improvements. System performance increased significantly, with average response times reduced by over forty percent during peak demand. Service availability improved, with planned downtime cut to near zero. Operational staff reported faster processing times and fewer workarounds, allowing them to focus more of their time on supporting customers rather than managing system limitations.

From a policy perspective, the new solution allowed changes to be implemented in days rather than weeks. This increased responsiveness meant the organisation could adapt more quickly to legislative updates and shifts in operational priorities. The cloud-based architecture also provided greater resilience, supporting automated scaling and improved disaster recovery capabilities.

The value of the transformation extended beyond immediate performance gains. The organisation now has a platform built on modern standards, enabling future enhancements, integrations, and service innovations. The shift to cloud infrastructure also reduced the long-term cost of ownership by decreasing reliance on bespoke legacy components and supporting more streamlined maintenance.

Knowledge transfer was a core success factor. Internal teams gained the skills and confidence to manage the platform, use monitoring dashboards, and evolve the service independently. This capability uplift ensures the benefits of the migration can be sustained and expanded over time.

“Their approach to knowledge transfer was exceptional. They didn’t just deliver a new platform — they brought our team with them, up-skilling us throughout so we could confidently own and maintain the solution after go-live.”

Technical Lead

Reflection

This project demonstrated the difference that collaborative, user-centred digital delivery can make in the public sector. By taking time to understand the system’s role within the wider service and by involving operational, technical, and policy teams throughout the process, we ensured the migration was both safe and strategically aligned.

Several themes emerged that will guide our future work. The first is the value of holistic discovery. Legacy systems often carry hidden dependencies and workarounds that only surface through deep engagement with users and frontline teams. The second is the importance of pairing technical expertise with strong change management. Technology alone is rarely the full answer; success depends on people being confident and capable in using the new tools. Finally, the project reaffirmed the importance of designing for sustainability. Delivering a modern solution is important, but ensuring teams can own and develop it long-term is what drives lasting improvement.

Our consultancy is proud of the role we played in enabling a smooth transition to a modern, cloud-based platform. The lessons learned from this engagement will continue to inform the way we support public sector organisations to modernise their services, strengthen resilience, and meet the evolving needs of the people they serve.