Principal AI Engineer – Hybrid London | Equity

Oliver Bernard; Greater London; Hybrid; GBP 198,000 - 242,000; Full time

Job summary

Oliver Bernard is hiring a Principal AI Engineer in London, hybrid, to own end-to-end model training, post-training, RL, evaluation and agent infrastructure. This is a hands-on individual contributor role with significant influence over technical direction and core systems.

The role demands strong experience with LLM training and production-grade AI, plus excellent software engineering skills (Python) and a track record of solving hard AI problems in top labs or high-bar startups.

Qualifications

• Experience with LLM training, post-training, RL or evaluation.
• Excellent software engineering fundamentals, ideally Python.
• Track record of solving difficult AI problems in production.

Responsibilities

• Lead major AI and research-engineering initiatives end to end.
• Build and improve training, fine-tuning and post-training pipelines.
• Develop evaluation systems, agent harnesses and feedback loops.
• Own technically ambiguous problems from experimentation through to production.
• Set technical direction while remaining close to code and models.

Skills

LLM training

RL/evaluation

Python

Production-grade AI

Senior IC level

Education

Master's or PhD in CS/ML/Math

Job description

Oliver Bernard is hiring a Principal AI Engineer in London, hybrid, to own end-to-end model training, post-training, RL, evaluation and agent infrastructure. This is a hands-on individual contributor role with significant influence over technical direction and core systems.

The role demands strong experience with LLM training and production-grade AI, plus excellent software engineering skills (Python) and a track record of solving hard AI problems in top labs or high-bar startups.