Our client, a mission-led consultancy , is looking for an experienced Principal Software Engineer (Python or Java) to join their growing team. They deliver secure, modern software solutions to the UK Government and Defence sectors, enabling clients to build scalable systems and progressive web applications that drive real impact. This is a senior-level opportunity for a hands-on engineer who enjoys leading by example , thrives in agile environments , and is passionate about shaping engineering best practice while still contributing to the codebase. Key Responsibilities Lead the design, development, and testing of secure, scalable systems using Python or Java with modern front-end frameworks (e.g., React)

Architect and maintain APIs, data pipelines, and cloud-native solutions (AWS, Azure, private cloud)

Drive adoption of DevOps practices CI/CD, containers, infrastructure-as-code

Guide and mentor engineers, promoting best practice, clean coding, and agile delivery

Collaborate with stakeholders and clients to shape technical direction and ensure robust, user-focused solutions

Contribute across the full software ...