Principal AI Engineer in England

Join a high-growth technology consultancy operating with start-up agility and major financial backing, building elite AI capability for UK national security.

Our client is a rapidly scaling defence technology consultancy operating with the speed, autonomy, and innovation mindset of a start-up, but with the backing and financial stability of significant institutional investment. This combination allows them to move quickly, invest heavily in capability building, and compete for some of the most technically challenging work in UK defence and national security.

The business is actively building out its Applied AI Engineering capability within its Defence practice and is hiring at Principal level to attract the brightest engineering and AI talent in the UK. This is a senior technical leadership role focused on delivering real-world, production-grade AI systems into mission-critical defence environments. The emphasis is on practical engineering impact: taking AI from prototype to production, ensuring reliability, and embedding it into secure operational systems.

You will work across high-impact programmes, shaping technical direction, influencing clients, and helping define how applied AI is used responsibly and effectively within defence contexts. Alongside delivery, you will play a key role in raising engineering standards and mentoring high-performing teams.

What You'll Be Doing

• Leading the design and delivery of AI-enabled solutions for defence and national security customers.
• Integrating AI components into existing applications, products, and operational workflows.
• Designing and implementing Retrieval-Augmented Generation (RAG) architectures.
• Evaluating Large Language Models (LLMs), identifying failure modes, and implementing mitigation strategies.
• Testing, validating, and debugging non-deterministic AI systems.
• Advising stakeholders on the risks, limitations, and appropriate use cases for AI technologies.
• Determining when statistical models, traditional machine learning approaches, or deterministic logic are more suitable than generative AI.
• Driving engineering best practice across AI development, deployment, governance, and observability.
• Providing technical leadership and mentoring senior engineers across the practice.
• Working closely with software engineers, architects, data specialists, product teams, and defence stakeholders.

Ideal Background

We are looking for exceptional technology leaders with deep engineering capability and strong applied AI experience. You should bring:

• 10+ years of technology industry experience with demonstrated technical leadership.
• Experience integrating AI capabilities into production applications and business workflows.
• Strong understanding of LLM architectures, machine learning models, and statistical methods.
• Practical experience building and deploying RAG solutions.
• Experience evaluating AI systems and improving reliability, safety, and performance.
• Strong software engineering, architecture, and systems design fundamentals.
• Experience working in complex, high-stakes, or regulated environments.
• Strong communication skills with the ability to influence senior stakeholders.
• Candidates must have graduated from a Top 300 global university.

What You'll Receive

• Salary between £100,000 and £140,000.
• The opportunity to join a high-growth defence consultancy operating with start-up speed and enterprise-grade backing.
• A chance to help build a leading Applied AI capability within UK defence.
• Exposure to some of the most complex and high-impact engineering problems in the country.
• Significant technical influence across programmes and clients.
• Flexible working arrangements and UK-wide location options.
• Rapid progression opportunities as the organisation continues to scale.

Who Should Apply

This role is suited to Principal Engineers, Staff Engineers, Principal Consultants, AI Engineering Leads, Machine Learning Engineering Leaders, Technical Architects, and senior software engineering professionals who want to work on applied AI in defence at scale. The business is actively hiring the brightest engineering and AI talent in the UK, with a strong preference for individuals who want to operate in high-ownership, high-impact environments. The team is based in Newcastle, which remains the preferred location. Strong candidates in Manchester, the South West, and across the UK will also be considered as the business expands its national footprint.

Security Requirements

Candidates do not need current DV Clearance but must be eligible to obtain it. Requirements include:

• British Citizenship.
• Minimum 10 years continuous UK residency.