If you're someone who loves the intersection of LLM systems, experimentation, and realworld product impact, this is the kind of role where your work won't stay hidden. You'll see it live, in customerfacing journeys, SEO performance, personalisation, 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 here 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 promptchains 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 contentoptimisation tool - improving product page copy for both relevance and discoverability
* Helping power personalised recommendations and messaging in our Personalisation squad
* Enhancing our Wellness Hub (our library of health articles and expert content) by generating, rewriting and improving pieces in safe, evidencebased ways
* Partnering with Data Engineering on context management, memory strategies, tool/functioncalling, observability and logging
* Monitoring and mitigating model drift, prompt degradation and system regressions
* Acting as a goto 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 higherquality health content that's 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 LLMpowered tools
* Clear evaluation metrics guide smarter, datadriven AI adoption
* LLM capability across H&B grows because you've helped demystify the technology
The Person
What you'll need
* Handson experience developing LLM applications beyond just prompt writing
* Solid data science foundations: experimentation, evaluation, statistical thinking, working with realworld datasets
* Strong understanding of: prompt optimisation, RAG, embeddings, vector stores, context management and LLM evaluation
* Very strong Python skills - this is a genuinely handson role
* Ability to reason about tradeoffs between quality, latency and cost
* Experience with Git, version control and CI/CD
* Confidence translating complex LLM concepts for nontechnical colleagues
* Curiosity, pragmatism, and comfort shaping a firstofitskind role
Benefits
Technology Incentive Scheme - we offer different bonus schemes for all grades in Technology, starting at 10%.
Learning and Development opportunity with Holland & Barrett is a great base for career development long term.
Career progression
Pension company contribution
Your wellbeing is paramount so you can get away and take 28 or 33 Days Holiday per year.
Refer and Earn Scheme - as we're growing you can earn money by referring people to join us from your network.
Epic Extras gives you access to exclusive benefits, free advice and savings from a range of retailers and providers.
Stay healthy with Discounted Products - from day one you'll get a 25% discount (on top of other promotions) when you shop at H&B on anything that you buy.
We all need a little help sometimes, so we offer Free 24/7 Confidential Advice & Colleague Welfare.
Mental Health First Aiders - we have lots of qualified Mental Health First Aiders because its all about your health & wellbeing.
We have colleague Reward and Recognition Schemes, so your hard work and loyalty won't go unnoticed.
And many more!