Portrait of Hannah Stewart

Hannah Stewart

Applied AI builder & facilitator

I build AI systems for mission-driven organisations, and teach the people around them to use AI well. As Senior AI and Technology Analyst at the Ellen MacArthur Foundation, I develop the LLM tooling behind the Foundation's research, most recently a retrieval pipeline that powers a published international policy analysis, and lead its organisation-wide AI transition: vendor evaluation, UK GDPR analysis, governance, and structured upskilling across a 200-person organisation.

Through Intersticia I design and facilitate AI ethics workshops that get people out from behind their screens and thinking critically about how these systems actually behave, including through Brave Conversations.

I started out as a web developer, spending three years shipping user-facing features in JavaScript and React on the Foundation's public website before moving into applied AI. I hold an MSc in the Social Science of the Internet from the University of Oxford, where I studied how the design of research tools shapes the way people seek and trust information, questions that now sit at the heart of LLM-mediated knowledge work.

Selected work

Circular by Nature: AI-assisted policy analysis pipeline

Designed, built, and validated the retrieval-augmented analysis pipeline behind Circular by Nature (EMF and the Latin America and Caribbean Circular Economy Coalition, 2026): GROBID PDF parsing, sentence-transformer embeddings indexed in FAISS, and a hierarchical roll-up architecture in which the model answers atomic evidence questions strictly from retrieved context before findings are synthesised upwards, so every conclusion stays traceable to source text. Validated against manually identified ground truth on pilot countries, then scaled to 31 policy instruments across 12 countries. The methodology is published as a standalone technical appendix.

The Simulation Game

An embodied workshop in which participants enact the support structure of a large language model: moving, speaking, and negotiating as the system they usually only type at. Designed to surface how AI reshapes group dynamics, it has been run with teams and audiences internationally, including at WebSci26, and is openly published as a documented, citable research instrument.

AI adoption and governance at EMF

Driving the Foundation's transition to enterprise AI: evaluating vendors against technical, security, and data protection criteria, authoring the AI Use Policy and governance framework with in-house legal counsel, and designing the literacy programme that took colleagues across every team from awareness to fluency.