Senior Research Engineer

Senior Research Engineer – Production AI Systems

London | In-office | Up to £300k base + significant equity

About Our Client

Our client is a very well-funded AI startup solving some of the hardest problems in production large language models. They're building systems that reliably handle complex, multi-step reasoning tasks at massive scale.

Their team combines talent from top-tier quantitative trading firms, leading AI research labs, and Big Tech. Backed by tier-one venture capital, they ship fast, maintain exceptionally high technical standards, and operate as an in-office team in London.

The Role

They're hiring a Senior Research Engineer to build and deploy core AI models from conception through production. You'll work on genuinely hard, unsolved problems: building LLMs that reason reliably across long contexts, maintain coherent state over extended interactions, and make sound decisions under uncertainty – all whilst serving millions of requests with strict latency requirements.

Hard Problems You'll Tackle

• Multi-turn reasoning and memory – Models that maintain coherent state across complex, extended interactions
• Production reliability at scale – Consistent, accurate behaviour serving millions of daily requests with sub-second latency
• Novel post-training methods – Training approaches optimised for real-world task completion, not benchmarks
• Real-time evaluation and orchestration – Systems that monitor quality and adaptively route between models in production
• Long-horizon task decomposition – AI systems that autonomously break down and execute multi-step problems

What You'll Bring

• 5+ years AI/ML engineering or research experience with production systems
• Hands-on post-training experience (RLHF, DPO, or similar) and deployed LLMs in production
• Strong Python and modern ML tooling (PyTorch/JAX, training infrastructure, evaluation pipelines)
• Track record shipping research from prototype to production impact
• Comfortable owning work end-to-end: architecture to data pipelines to production integration

Why Join

• Work on genuine research problems that ship to production within weeks
• Collaborate with exceptional engineers from elite quant firms, frontier AI labs, and top tech companies
• Own multi-quarter initiatives and shape the research roadmap
• Up to £300k base + significant equity
• In-office in London with some of Europe's best AI talent

For more information, or a discreet chat regarding the market/similar roles, please get in touch:

James@durlstonpartners.com