Principal AI Engineer

Principal AI Engineer Location: London Salary: Up £155,000 About the Company An ambitious, venture-backed AI technology company transforming a traditional industry through the application of cutting-edge artificial intelligence. Having secured significant early traction, they're entering an exciting phase of growth and are looking for a Principal AI Engineer to lead the evolution of their AI platform. This is a rare opportunity to join an early-stage business where you'll have genuine ownership over the technical direction of the platform, working alongside founders and senior leadership to build AI products that deliver real commercial impact. The Role As Principal AI Engineer, you'll take ownership of the architecture, design and development of the company's AI platform, building the infrastructure that powers intelligent workflows, AI agents and next-generation customer experiences. This is a highly hands-on role suited to someone who enjoys solving complex technical challenges, building scalable systems from first principles and taking AI products from concept through to production. You'll play a key role in shaping both the technical roadmap and engineering standards while helping build a world-class AI capability. Key Responsibilities * Design, build and scale the company's AI platform and supporting data infrastructure. * Develop production-grade LLM applications, agentic AI systems and RAG architectures. * Build scalable data pipelines, orchestration frameworks and AI workflows capable of supporting enterprise-scale products. * Architect secure, multi-tenant cloud-native applications with high availability, observability and performance. * Implement robust evaluation frameworks, monitoring, guardrails and governance for production AI systems. * Optimise AI performance, latency and cost across multiple model providers. * Collaborate closely with Product and Leadership teams to translate business challenges into scalable technical solutions. * Drive engineering best practice across architecture, CI/CD, testing, security and platform reliability. * Mentor engineers and contribute to the growth of a high-performing engineering function while remaining technically hands-on. Technology Stack Experience across many of the following technologies would be advantageous: * Python * FastAPI * TypeScript * React / Next.js * PostgreSQL * SQL * AWS and/or GCP * BigQuery * REST APIs * ETL and Data Pipelines * CI/CD * LangGraph * Model Context Protocol (MCP) * OpenAI * Anthropic * Gemini * RAG * Vector Databases * Agent Orchestration * AI Evaluation Frameworks * Monitoring \& Observability * Airflow or Dagster (desirable) * Kubernetes (desirable) About You My client is looking for someone who can demonstrate: * Extensive experience designing and deploying production AI systems. * Strong software engineering and solution architecture expertise. * Hands-on experience building LLM-powered applications, AI agents and modern AI platforms. * Experience designing scalable cloud-native systems and data platforms. * A strong understanding of AI architecture, model evaluation, retrieval strategies and production deployment. * Commercial awareness with the ability to balance technical excellence against business objectives. * Previous experience within a startup or high-growth technology environment. * Excellent communication skills with the ability to influence technical and non-technical stakeholders. Desirable Experience * Multi-agent AI architectures. * Large-scale RAG implementations. * Experience building internal AI tooling or developer platforms. * Experience working within regulated environments. * Previous exposure to fundraising, technical due diligence or scaling engineering teams. * A degree in Computer Science, Engineering, Mathematics or a related discipline from a leading university is highly desirable. Candidates from Oxford, Cambridge, Imperial or Warwick would be of particular interest, although equivalent commercial experience will also be considered.