Lead ML Engineer — Production AI & LLMs

Company: Cleo AI
Apply for the Lead ML Engineer — Production AI & LLMs
Location: London
Job Description:

Requirements

  • Experience deploying multiple machine learning models into production
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  • 5+ years of experience in data science, machine learning engineering, or related roles
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  • Experience integrating and evaluating LLMs
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  • Excellent knowledge of both Data Science (Python, SQL) and production tools
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  • Understanding of probability and statistics fundamentals
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  • Strong ability to communicate findings to non-technical stakeholders
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  • Experience of leading projects involving multiple people including developing a short term roadmap and reporting progress
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  • Comfortable breaking down work incrementally
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  • (Desirable) Familiarity with Docker containers and container orchestration tools
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  • (Desirable) Experience with LLM-as-a-judge and/or annotation pipelines
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  • We strongly encourage applications from people of colour, the LGBTQ+ community, people with disabilities, neurodivergent people, parents, carers, and people from lower socio-economic backgrounds

What the job involves

  • Machine Learning Engineers at Cleo work on building novel solutions to real-world problems
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  • This really does vary but could be: creating chatbots to coach our users around their financial health, creating classifiers to better understand transaction data or even optimising transactions within our payments platform
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  • They train, deploy, and improve machine learning models in production, ensuring they deliver meaningful impact for our users
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  • We’re looking for our next Lead Machine Learning Engineer to join our Chat Evaluations team
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  • You’ll shape & guide technical work within a team of adaptable, creative and product-focused engineers, who deliver ML/AI features that improve the observability of chatbot quality and power the AI development cycle
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  • Here are some examples, big and small, of the kinds of product feature work our ML Engineers have taken part in over the last year:
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  • Deployed best-in-class credit decisioning models which affect millions of customers, using open banking data rather than traditional credit scoring
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  • Developed models to interpret transactional data, enhancing the understanding of users’ finances. Think about your bank statement—how often do you not recognise a transaction on first review?
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  • Fed user interaction data into fine-tuned LLMs and contextual ranking models, so Cleo knows how to start and continue an engaging conversation
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  • Developed optimisation models to improve payment success rates for customers while minimising business costs, tackling this as a two-sided optimisation challenge
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  • Designed and implemented AI agents to analyse and extract insights from users’ transactional data

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Posted: May 28th, 2026