Staff AI Engineer — LLM Research & Agentic Systems

Oliver Bernard; Greater London; On-site; GBP 180,000 - 220,000; Full time

Job summary

Oliver Bernard’s client, a stealth-mode AI startup in London, is hiring a Staff AI Engineer to tackle challenging problems across LLMs, reinforcement learning, and agentic systems. This hands-on role blends research and engineering, contributing to both model development and production-grade systems.

You will work on LLM training and fine-tuning, evaluation loops, agent development, and AI research, applying strong software engineering to complex AI problems.

Qualifications

• Experience 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.
• Strong track record in AI research and solving technically complex problems.

Responsibilities

• Work on LLM training and fine-tuning, including RL and post-training.
• Develop evaluation loops to continuously assess and optimise models.
• Design and build sophisticated AI agents and agentic systems.
• Contribute to AI research, exploring training, RL, evaluation and optimisation techniques.
• Apply strong software engineering fundamentals to complex AI problems.

Skills

LLMs

Training & Fine-tuning

Reinforcement Learning

Agent development

Model evaluation

Software engineering

AI research

Python

PyTorch

TensorFlow

Tools

Python

PyTorch

TensorFlow

Job description

Oliver Bernard’s client, a stealth-mode AI startup in London, is hiring a Staff AI Engineer to tackle challenging problems across LLMs, reinforcement learning, and agentic systems. This hands-on role blends research and engineering, contributing to both model development and production-grade systems.

You will work on LLM training and fine-tuning, evaluation loops, agent development, and AI research, applying strong software engineering to complex AI problems.