Principal Engineer (Gen AI and MACH Architecture)

At AKQA (part of WPP), we believe in the imaginative application of art and science to create beautiful ideas, products and services. With an entrepreneurial and collaborative approach, we design and build adaptive digital products, services and experiences that capture the imagination and deliver impressive returns for our clients. We are looking for a senior, architecture-led Principal Engineer to join our London Technology team. This is a hands-on engineering role, not a strategy-only or evangelism position. You will spend the majority of your time designing, building and shipping enterprise-grade systems, with roughly 65 to 70% hands-on delivery and 30 to 35% technical leadership, architecture and team guidance. You will lead the technical direction of complex client programmes across MACH architectures and production Generative AI; spanning Design to Code workflows, solution design and API contracts through to cloud infrastructure, deployment and ongoing operation. You will own architecture decisions, write and review production code, and mentor engineers, while remaining accountable for what ships, not just what is proposed. Production Generative AI experience is essential. You must have at least three years' experience working with Generative AI, and have delivered at least one AI capability into a live, enterprise environment; not limited to prototypes, proofs of concept or demo builds. We need engineers who understand retrieval pipelines, evaluation, cost, governance and operational reliability at scale; including where custom model creation, fine-tuning or adaptation is required for production delivery. AKQA is advanced in Design Systems and Design to Code practice; from Figma design systems through to UI development and application delivery. Generative AI is increasingly embedded across this design-to-application workflow, accelerating the path from design intent to production-ready code and experiences. The Principal Engineer (Tech Lead) is a key technical contributor across the programme lifecycle, working closely with Technical Managers, cross-discipline teams and on-shore, off-shore and hybrid engineering squads. This role sits at Principal or Staff Engineer seniority, aligned with our Technical Managers and Technical Architects in scope and influence. While client-facing and influential, the role is technologist-first. You may occasionally support pre-sales scoping or technical pitches, but your primary value is deep engineering craft, sound system design and reliable enterprise delivery. Technical architecture and hands-on engineering capability are mandatory. Based in London (Farringdon), in a hybrid working environment, frequently collaborating with our global studios and partners, you will enjoy working in a team of highly skilled people, all with strong opinions about various technologies, frameworks and approaches. You will articulate your ideas to colleagues effectively whilst also taking on board the ideas of others and remaining solutions focused. You will thrive when faced with new challenges, view them as opportunities and constantly look to improve client offerings. You will work in a progressive environment that fosters a meritocratic culture, surrounded by some of the brightest minds in their fields. As a Principal Engineer (Tech Lead) at AKQA, you will be inspired by technology and have a passion for building robust, scalable solutions that perform in production. ROLE REQUIREMENTS Generative AI and Intelligent Experience Architecture • Minimum three years' experience with Generative AI, including proven experience shipping at least one AI solution to production in an enterprise context (beyond prototypes or sandbox experiments). • AI architecture for experience platforms: system design f