423,897 lines
The measured C# source corpus used as the workload reference.
The economics of modernisation
Understanding the application has a cost before changing it has a cost.
Modernisation economics are often discussed in terms of delivery. A significant cost appears earlier: establishing enough reliable understanding of the existing application to decide what should change.
Harten measures that work directly: application size, elapsed analysis time, infrastructure and AI consumption, specialist review effort and the outputs produced.
Indicative economics
The cost is not just the model. It is the whole analysis.
The figures below are indicative scenarios for comparing methods on a complex enterprise application. They show how different approaches allocate time and cost; actual engagements vary with application complexity, evidence quality, access and scope.
| Method | Indicative elapsed time | Indicative cost | Main cost drivers |
|---|---|---|---|
| Traditional analysis | 8–12 weeks | £87k–£131k | Architect, engineering and analysis time |
| Frontier-agent-assisted analysis | 3–6 weeks | £36k–£75k | Specialist labour plus repeated AI reasoning |
| Harten analysis + bounded proof of concept | 3 weeks | £29k–£60k | Application analysis, bounded proof of concept, compute, AI consumption and specialist review |
The traditional scenario uses a four-person team: one solutions architect, two software developers and one business analyst. Current UK advertised contract medians are approximately £625/day for a solutions architect, £525/day for a software developer and £500/day for a business analyst. That produces a modelled team cost of about £2,175 per working day. The frontier-agent-assisted range assumes materially less elapsed human effort but adds AI consumption; actual usage varies significantly with model, context, retries and the work delegated to agents.
UK Solutions Architect contract rates — IT Jobs Watch · UK Software Developer contract rates — IT Jobs Watch · UK Business Analyst contract rates — IT Jobs Watch
These are comparison scenarios, not promises of project duration, price or savings. Application complexity, evidence quality, access, review requirements and scope can materially change the result.
Measured example in progress
A complex enterprise application provides the first worked comparison.
The current analysis covers a 423,897-line C# application. For comparison, the indicative Harten scenario is three weeks and £29k–£60k, compared with 3–6 weeks and £36k–£75k for frontier-agent-assisted analysis. The Harten scenario allocates the first week to application analysis and weeks two and three to review, clarification and a bounded proof of concept. The comparison therefore reflects both lower modelled cost and more work completed within the engagement, rather than treating faster analysis as the only benefit. These figures are indicative planning scenarios rather than quotations or guarantees.
One analysis VM
The current run uses a single 8-vCPU, 168 GiB RAM virtual machine.
One week for analysis
The commercial scenario allows a full week for application analysis, including contingency and review of the analytical output.
Weeks two and three: bounded proof of concept
Use the established application understanding to test a selected change or modernisation path, with scope and acceptance criteria agreed for the engagement.
The comparison is indicative rather than a quotation or guarantee. Scope, access, application complexity and review requirements can change both cost and elapsed time.
The economic question
What did it cost to establish enough understanding to make the next decision?
That denominator lets organisations compare specialist labour, AI consumption and compute without assuming that any one of them is free.