Principal Software Engineer in Bristol

Our client is a defence technology company.
We're building the UK's next generation engineering powerhouse, providing critical technology that strengthens national security and resilience.
We specialise in turning advances in sensing, AI, and communications into operational capability for the edge, where connectivity may be degraded or denied. Our work focuses on accelerating the deployment of technology, improving decision-making for frontline teams, and protecting people and critical assets in demanding environments.
Headquartered in Bristol, our client employs around 200 people and operates over 20,000 square feet of engineering and manufacturing facilities. We have a growing international footprint and are one of Europe's fastest-growing engineering businesses.
About the role
We are looking for a Principal Software Engineer to build the Internal Developer Platform that our engineering teams depend on - a platform built from the ground up for agentic engineering. Our software teams work on hard problems under tight deadlines. Your job is to make sure the platform underneath them is not one of those problems.
Working within the Platforms team, you will architect and own the tooling, infrastructure, workflows, and components that our client's developers build on. That means repeatable development environments, paved paths that are faster than the alternatives, and platform services that teams adopt because they want to, not because they have to.
You will lead the implementation of agentic AI and passionately advocate for its use: rolling out coding agents, embedding them into CI/CD and day-to-day development, and building the harnesses and infrastructure that let them run securely, efficiently, and transparently. You will track new developer tooling and agentic AI closely, adopt what works before most teams have heard of it, and enjoy convincing others to do the same. This role gives you a whole engineering organisation to do that for.
This is some of the highest-impact engineering in the company. It is not a delivery role. You will not be assigned to customer projects, and you will not review delivery PRs. Your users are our client engineers, and the platform is the product.
Candidates must be eligible for SC clearance.
More information about security clearance is availab...