Data and AI

Legacy system modernisation

Making legacy systems visible, validated and safe to rebuild

Many public services still run on systems that nobody fully understands. Storm ID has built its own AI delivery method to change that. Our specialist AI agents uncover what a legacy system does. Your people confirm every finding. Then we rebuild it as a modern service that your organisation can explain, change and trust.


You cannot modernise a service you cannot explain

Legacy systems hold years of policy, workarounds and decisions that were never written down. That logic sits in places that conventional discovery struggles to reach:

  • Source code, stored procedures and batch processes
  • Spreadsheets and macro-enabled workbooks
  • Policy documents, manuals and the knowledge of long-serving staff
  • Systems where the original supplier, or the source code, is no longer available

So, modernisation keeps getting deferred. The old system costs more to run each year, the people who understand it retire, and the risk grows quietly. Across Scotland’s public sector, around £3.80 goes on running existing technology for every £1 spent on changing it.

AI changes the economics, but only when it is applied with discipline. We use AI to do the slow, expensive work of discovery, specification and build with far less effort. Every finding then goes to people who know the service before anything is built. You start with evidence, not with a target platform.


Our IP: a delivery method we have built and own

Most AI tools help an individual work faster. We have gone further and turned Storm ID’s whole delivery method into a system that runs the same way on every project.

  • Agents do the work. We have built eight AI agents, each trained for one role on a delivery team: business analyst, user researcher, UX designer, content designer, tech lead, two architects and a test writer. Each agent has written instructions for its role, like a job description and a playbook combined.
  • Skills hold our know-how. We have written down 40 pieces of specialist knowledge that the agents draw on. These include how we write .NET and Node code, how to build prototypes to Scottish Government and GOV.UK design standards, how to write secure code, and how to test a service so nothing breaks when it changes. Each project switches on only the skills its technology needs.
  • Gates keep quality high. Every project moves through the same stages: Discovery, Prototype, and Build and Test. Each stage has a gate. Before work can pass, the required outputs must exist, automated checks must pass and a named person must approve them.
  • How it works in practice. Say the Discovery Accelerator finds an eligibility rule hidden in an old spreadsheet macro. The business analyst agent writes it up as a plain-English requirement and links it back to the cell it came from. Your service owner confirms the rule is still correct. Later, the test agent writes a test that proves the new service applies the rule in exactly the same way. A person signs off at every step, and you can trace the rule from old system to new.
  • Why this is valuable. Because the method is written down, the quality of your project does not depend on which people we put on it. Every project follows the same standards and checks. And because it is shared across all our work, every improvement we make on one engagement is ready for the next.

Key benefits

  • Understanding before commitment

    Know what your system really does, which rules matter and what it will cost to change. You learn this before you choose a platform or set a deadline.
  • Faster, lower-cost delivery

    Our agents and skills cut the effort of discovery, specification and build. On our own delivery, we have measured around 40% less effort than a conventional approach.
  • Evidence you can audit

    Every finding can be traced to its source. The chain runs from the legacy code or policy to the requirement and the test that replace it, and every gate leaves a record.
  • Consistent quality, every time

    Because the method is encoded rather than held in individual heads, every project follows the same standards, checks and conventions. Quality does not depend on which team you get.
  • Modernise the service, not its constraints

    We decide what to preserve, improve, retire or introduce. That way you don’t rebuild limits that only existed because of old technology.
  • Lower operational and cyber risk

    Replace fragile, unsupported systems before they fail, and depend less on a shrinking pool of specialist skills.
Bar chart: the saving is largest where the work is reading and writing code, smallest where people must decide. Effort saved against conventional delivery on one UK public sector programme delivered AI-first: AI-assisted Alpha build 71%, front-end prototyping 65%, requirements elicitation and definition 44%, technical architecture and design documentation 32%, project management and stakeholder engagement 7%, testing 0%. 40% across the programme. Source: Storm ID delivery data.

How it works

Six steps take you from an opaque legacy system to a live service. Our agents, skills and gates sit behind each one.

  1. 1
    Discover
    Our Legacy Discovery Accelerator turns code, data, spreadsheets and documents into an evidence pack. Specialist agents for business analysis, user research and architecture draft the requirements, user needs and feasibility findings.
  2. 2
    Validate
    Your service owners and specialists confirm, correct or reject each finding. Nothing moves forward on AI output alone.
  3. 3
    Decide
    Choose what to preserve, improve, retire or introduce, one component at a time. Decisions are recorded and carried into the high-level and low-level design.
  4. 4
    Specify
    Turn the validated rules into testable requirements and acceptance criteria. Working prototypes, built to Scottish Government or GOV.UK design standards, let users test the service before it is built.
  5. 5
    Modernise
    Rebuild feature by feature using AI-assisted engineering, with a secure coding guard, automated regression tests, independent code review and a controlled deployment gate.
  6. 6
    Measure
    Track how the service performs, then reuse the method on the next system. Every improvement we make goes back into the shared method.
“AI changes how fast we can modernise. It doesn’t change the standard a public service has to meet before it goes live.”

Where legacy modernisation delivers impact

Central government

Replace fragile workbooks and bespoke applications that sit behind casework, grants and operational services.

Justice

Modernise case management and the data flows between bodies, with the auditability the justice system requires.

Health and care

Move legacy administrative systems onto modern, secure platforms without disrupting patient services.

Local government and public bodies

Deal with the long tail of ageing line-of-business systems that hold back service redesign.

Built for trust

  • AI output is treated as a draft until people confirm it, and a person approves every output at every gate
  • Independent reviewers check prototype fidelity and code quality before work moves on
  • UK government standards checks and a secure coding guard run as part of the method, not as an afterthought
  • Sensitive material stays under your control, and data is minimised before any analysis
  • Analysis runs in approved environments with identity controls, MFA and least-privilege access
  • Model providers retain none of your data
  • AI is used to build the service, not as something the live service depends on
  • Delivered under ISO 27001 and ISO 9001 certified processes

Why now is the time to act

  • Standing still keeps getting more expensive. Most legacy budgets go on keeping systems running, not on improving them.
  • Specialist knowledge is leaving. The people who understand older systems are retiring faster than they can be replaced.
  • AI has changed the payback. In our modelling, payback on a legacy system costing £1m a year falls from about 10.5 years to 6.3 years.
  • Reform depends on it. Better services and lasting savings need systems that can change.

Storm ID helps you move from deferral to delivery. You start with one system and measure the results before you scale.

Line chart: AI brings the payback forward by four years. For an illustrative system costing £1m a year to maintain and saving £286k a year once replaced, a £3.0m conventional rebuild breaks even after 10.5 years, while a £1.8m AI-first rebuild breaks even after 6.3 years. Across the 15 to 60% range of savings, AI-first break-even falls between 4.2 and 8.9 years. After 10 years, AI-first is £1.1m ahead and conventional is still £0.1m behind. Sources: UK Parliament (2026); Storm ID delivery data.

Why Storm ID

For over two decades, Storm ID has delivered secure digital services for public sector and regulated organisations. We are an AI-first consultancy, and we have invested in our own delivery IP rather than relying on generic tools alone.

We developed this method on live public sector work, delivering modern digital services. Each engagement has made the method stronger, and every client benefits from what we learned on the last one.

We combine AI-led discovery with the engineering discipline, governance and assurance that public services demand. We are a Microsoft Solutions Partner for Data & AI, and a member of Anthropic’s Claude Partner Network and an OpenAI Select Partner.

the Foreign, Commonwealth & Development Office
Historic England
Crown Office & Procurator Fiscal Service
The Scottish Parliament
NHS Forth Valley
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ISO 9001 certification logo
ISO 13485 certification logo
ISO 14001 certification logo
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Cyber Essentials Plus
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Start with one system

Modernisation doesn’t have to begin with a programme. It can begin with one service that proves the approach. Bring us a legacy system and we will show you what our method finds, what it would take to replace and what it would save.