Senior Machine Learning Engineer

Senior LLM Engineer - London Hybrid (2 days per week on-site, Bank area)

My client is a long-established consultancy that originally built its reputation in data engineering and wider data transformation, and over the past few years has grown a strong applied AI practice. They tend to work with UK organisations where data security, reliability and explainability actually matter, so think regulated, risk-aware, or operationally critical environments rather than hype-driven MVPs.

The current AI/ML group is around eight senior engineers, with backing to grow sensibly (not a hiring spree). This role sits within that team and is focused on designing and deploying LLM systems that make it into production, are cost-efficient, and work reliably in the real world.

What you'll be doing:

• Owning the design and build of LLM-based systems end-to-end

• Fine-tuning and adapting models (LoRA, instruction tuning, PEFT etc) rather than just prompt-engineering

• Building RAG workflows, embedding strategies, memory layers and domain grounding

• Working out how to measure output quality, reduce hallucination risk and improve robustness

• Optimising inference performance (quantisation, distillation, pruning, batching, caching)

• Deploying models into production environments where latency, cost and privacy are real constraints

• Working closely with both internal engineers and client teams to ensure what gets built actually lands well

What they're looking for:

• Hands-on LLM experience beyond prototyping / notebooks

• Strong Python and experience with PyTorch / Hugging Face / similar tooling

• Experience deploying models into production (not just training them)

• Familiarity with vector stores and RAG patterns

• Comfortable operating in a hybrid environment and speaking with stakeholders where required

• Someone who enjoys solving real problems end-to-end: from understanding the domain designing the approach shipping the implementation

• Experience of MLFlow / MLOps highly desirable

Important notes (just to be upfront):

• They cannot sponsor visas, so you'll need existing right to work in the UK

• No relocation support - you'll need to already be UK-based and able to be in London (Bank area) twice a week

• This is a senior role - typically someone with 3+ years' experience in ML/AI roles, ideally from a data science or applied ML background

Benefits / set-up:

• Modern kit (MacBook etc.)

• 27 days annual leave + bank holidays

• 4-week paid sabbatical after 4 years' tenure

• Regular team meet-ups, workshops, and knowledge-sharing sessions

• Sensible working hours - grown-up environment, not crunch culture

• Clear progression as the AI group continues to scale

• Stable team, low-ego culture, and work that isn't just slideware or demos