Artificial Intelligence Engineer

Senior AI Engineer– LLM & Production Systems

London | Office-first (4 days/week)

A well-funded UK AI start-up is hiring an AI Engineer as it scales a platform that uses large language models to simulate real human behaviour. The team has recently moved into a new London office and is growing quickly off the back of strong early traction and customer demand.

This role sits at the centre of the business: taking research and experimental AI work and turning it into reliable, production-grade systems that customers depend on for high-stakes decisions.

The Role

• Take AI and research prototypes and turn them into robust, scalable production systems
• Build, operate and improve LLM-driven agent systems, including memory, context and orchestration layers
• Make clear technical decisions around model behaviour, performance trade-offs, evaluation and failure modes
• Own systems end-to-end: from early design through deployment, monitoring and iteration
• Work closely with scientists, engineers and founders in an office-first, highly collaborative environment

Example projects you might work on include:

• Turning a research prototype into a production LLM agent with proper context management, evaluation and monitoring
• Diagnosing why an agent’s outputs degrade under real user traffic and improving reliability through prompt, retrieval or workflow changes
• Designing multi-step agent workflows where models retrieve, reason, and act rather than generating single-shot responses
• Improving system behaviour when models hallucinate, hit context limits, or fail on edge cases
• Making pragmatic trade-offs between accuracy, latency and cost in production environments

What You’ll Bring

• Strong backend engineering experience (Python, APIs, production systems)
• Hands-on experience building applications on top of LLMs (agents, RAG, workflows, prompting)
• A practical understanding of how models behave in real usage, including limitations and edge cases
• Experience debugging, evaluating and improving LLM outputs over time
• Ability to explain complex technical decisions clearly to non-technical stakeholders
• Comfort operating with incomplete information and taking ownership of open-ended problems

What’s On Offer

• Competitive salary depending on experience (with meaningful equity)
• Office-first setup in central London (4 days/week)
• Small, senior team with direct access to both technical and commercial founders
• The opportunity to work on real-world AI systems used by major organisations
• Long-term progression as the company scales its platform and applied research capability