Staff AI Engineer - Stealth Start-up - London

🚀 Staff AI Engineer | Stealth Mode AI Start-up | London | Up to £200k Oliver Bernard have partnered with a stealth-mode start-up in the AI \& Research space , who are looking for a Staff AI Engineer to join the team and work on some genuinely challenging problems across LLMs, reinforcement learning and agentic systems. This is a hands-on research + engineering role, where you’ll be involved in: 🧠 LLM training \& fine-tuning – including reinforcement learning and post-training 🔄 Evaluation \& feedback loops – building systems to continuously assess and optimise models 🤖 Agent development – designing and building sophisticated AI agents 🔬 AI research – exploring LLM training, RL, evaluation and optimisation techniques 💻 Software engineering – applying strong engineering fundamentals to complex AI problems What they’re looking for: * Strong experience working with LLMs and/or foundation models * Deep experience with training, fine-tuning, RL or post-training * Strong background in model evaluation and optimisation * Experience building AI agents / agentic systems * Excellent software engineering fundamentals * A strong track record in AI research and solving technically complex problems 📍 London – 2 days hybrid 💰 Up to £200k If you’re a Staff-level AI Engineer who wants to work at the intersection of cutting-edge research and production engineering, apply below for more information. London | Stealth | Staff AI Engineer