LLM Data Scientist

About Data At Holland & Barrett

Location: Hybrid working – occasional office presence. London or Nuneaton when required.

Holland & Barrett is investing heavily in the next generation of digital and AI capability - not as an experiment, but as a core part of how we help millions of customers live healthier lives. We're now hiring our first LLM Data Scientist to shape how LLMs show up across the business - on our website, in our content, in our recommendations, and in the tools our teams use behind the scenes.

The Role

If you love the intersection of LLM systems, experimentation, and real‑world product impact, this is the kind of role where your work won't stay hidden. You'll see it live, in customer‑facing journeys, SEO performance, personalization, and in the quality of the content we publish. And to be clear: this is not a role for someone who has only ever engineered prompts in isolation. You'll definitely write prompts - but the value comes from understanding how LLMs behave in real systems, with real data, and knowing how to evaluate, measure, optimise and deploy them at scale. If you have the data science mindset and the LLM engineering skillset, this is where you can genuinely shape things.

What you'll actually be doing:

• Designing, testing, and optimising prompts and prompt‑chains for production LLM applications
• Building evaluation frameworks to measure quality, safety, relevance, latency and cost
• Working with RAG architectures, embeddings and vector databases to improve retrieval and contextual accuracy
• Owning and developing our SEO content‑optimisation tool - improving product page copy for both relevance and discoverability
• Helping power personalised recommendations and messaging in our Personalisation squad
• Enhancing our Wellness Hub by generating, rewriting and improving pieces in safe, evidence‑based ways
• Partnering with Data Engineering on context management, memory strategies, tool/function‑calling, observability and logging
• Monitoring and mitigating model drift, prompt degradation and system regressions
• Acting as a go‑to LLM expert across the business, helping teams understand what’s possible and what’s not
• Staying close to the evolving LLM landscape and translating new ideas into useful, practical improvements

How We'll See Your Impact:

• Customers engage more with product pages because the content is more helpful and tailored
• SEO performance improves thanks to your optimisation tools
• We publish higher‑quality health content that is accurate, engaging and aligned with our brand
• Customers receive more relevant recommendations at the right moment
• Internal teams work faster thanks to stronger, more reliable LLM‑powered tools
• Clear evaluation metrics guide smarter, data‑driven AI adoption
• LLM capability across H&B grows because you've helped demystify the technology

What You'll Need:

• Hands‑on experience developing LLM applications beyond just prompt writing
• Solid data science foundations: experimentation, evaluation, statistical thinking, and working with real‑world datasets
• Strong understanding of prompt optimisation, RAG, embeddings, vector stores, context management and LLM evaluation
• Very strong Python skills – this is a genuinely hands‑on role
• Ability to reason about trade‑offs between quality, latency and cost
• Experience with Git, version control and CI/CD
• Confidence translating complex LLM concepts for non‑technical colleagues
• Curiosity, pragmatism, and comfort shaping a first‑of‑its‑kind role

Benefits

Wellbeing & Lifestyle Benefits:

• 33 days holiday, including bank holidays
• Health Cash Plan
• Life Assurance
• Incentive scheme based on company & personal performance
• Virtual GP
• Private Medical care
• FREE at-home blood test kit
• Holiday Purchase option
• Pension Contribution scheme
• Access to ‘Wellhub' with gyms, studios and wellbeing apps

Discounts & Savings:

• 25% Colleague Discount with FREE Standard Delivery
• Exclusive Discounts from a wide range of partners
• £/€50 Annual Product Allowance to spend in store

Learning & Development:

• Access to a variety of learning opportunities, including Level 2-5 Apprenticeships, Workshops and our Digital Learning Library