Principal AI Engineer

Defence | AI | Agentic Systems | Deep Tech | Mission-Critical Technology

Are you an experienced AI Engineer who wants to do more than build another chatbot, LLM wrapper or internal productivity tool?

We're partnered with one of the UK's most exciting and well-funded deep-tech companies, developing advanced AI and simulation technology used across defence, national security and government environments.

They're entering a significant phase of growth and are building a new generation of AI-powered products combining LLMs, agentic workflows, advanced simulation and complex real-world data to solve problems where the technology genuinely matters.

They're now looking for a Principal AI Engineer to become one of the senior technical voices within the AI function - remaining deeply hands-on while helping shape architecture, engineering standards and the technical direction of their AI capability.

This is an opportunity to have significant ownership in a rapidly evolving AI environment rather than simply joining an established team and maintaining what already exists.

What You'll Be Doing

• Acting as a senior technical authority across AI engineering and architecture.
• Designing and delivering production-grade AI systems for complex, mission-critical environments.
• Building sophisticated applications using LLMs, RAG, agentic workflows and AI orchestration .
• Defining architecture and technical direction for new AI capabilities.
• Evaluating emerging models, frameworks and approaches and determining where they can create genuine value.
• Taking AI solutions from experimentation and prototypes through to robust production environments.
• Working closely with Product, Engineering and Domain Experts to solve complex customer problems.
• Setting engineering standards and best practices across AI development, evaluation and deployment.
• Mentoring senior engineers and raising technical capability across the wider team.
• Remaining highly hands-on with engineering while influencing longer-term technical strategy.

What We're Looking For

• Significant commercial software engineering experience with a strong track record building production AI/ML systems .
• Deep hands-on experience developing applications using LLMs and modern Generative AI technologies .
• Strong understanding of RAG architectures, agentic workflows, LLM orchestration, evaluation frameworks, prompt engineering and fine-tuning .
• Excellent Python engineering skills, with TypeScript/Node.js experience highly valuable.
• Proven experience designing AI architectures and making high-level technical decisions.
• Experience taking AI products from early experimentation through to production.
• Comfortable operating in an environment where the architecture, tooling and frameworks are still evolving.
• Strong communication skills with the ability to explain and defend technical decisions.
• A customer and problem-first mindset - understanding the problem before reaching for the latest AI technology.
• Experience mentoring engineers and influencing technical direction without moving away from hands-on engineering.
• Ability to obtain UK Security Clearance (SC) .

Nice to Have

• Experience within defence, national security, aerospace, simulation or other mission-critical environments.
• Experience building multi-agent or autonomous AI systems .
• Knowledge of C++ or Rust.
• Experience working in an early-stage AI function or as one of the first senior AI engineers within a startup or scale-up.
• Exposure to simulation, digital twins, command & control or complex distributed systems.

Why Join?

• Join at a pivotal stage as the organisation significantly expands its AI capability.
• Become a key technical voice shaping how AI is engineered across the business.
• Work on AI problems far beyond standard chatbot and LLM-wrapper applications.
• Build technology operating at the intersection of AI, simulation, defence and national security .
• Work alongside exceptional engineers on genuinely complex technical challenges.
• Significant technical ownership with the freedom to influence architecture and engineering direction.
• Fast-moving scale-up environment where ideas can reach production quickly.
• Highly flexible hybrid working model with a London office.
• Enhanced pension.
• Share options.
• Dedicated learning and development budget.
• Enhanced parental leave.
• Additional Christmas shutdown days.

Ready to help define the next generation of AI-powered defence and simulation technology?

Recognition One and our clients are proud to be equal opportunity employers. We will consider qualified applicants without regard to race, colour, creed, religion, sex, sexual orientation, gender identity, national origin, citizenship, disability status, medical condition, pregnancy, protected veteran status or any other characteristic protected by applicable law. We will also consider qualified applicants with arrest and conviction records consistent with local law.

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