Lead Software Engineer

Location: South East London

Lead Software Engineer Active SC Clearance Essential Our client, an innovative UK technology company is building a next-generation AI platform for defence and health applications . Their systems operate in highly regulated, mission-critical environments where reliability, security, and performance truly matter. Were looking for a Lead Software Engineer to take technical ownership of key platform components, guide architectural decisions, and mentor engineers as we scale.

This is a hands-on leadership role youll be writing code, shaping systems, and directly influencing the future of the platform. This is a genuine ground-floor opportunity to shape both the technology and the engineering culture within a growing, mission-driven business. What Youll Be Working On Leading the design, development, and evolution of intelligent, distributed systems Architecting and building AI-driven capabilities , including:
Large Language Models (LLMs) Retrieval-Augmented Generation (RAG) AI agents and orchestration workflows Designing and maintaining backend services and APIs (primarily Python, FastAPI / Flask) Building and scaling data pipelines and search systems using:
Elastic Search, Weaviate, Pinecone, and other vector databases Engineering secure, containerised architectures using Docker and Kubernetes Ensuring high availability, fault tolerance, and performance for mission-critical workloads Providing technical leadership and mentorship to other engineers Contributing to technical strategy, tooling choices, and engineering best practices

What Were Looking For Essential Active SC clearance and British nationality (no dual nationality) Degree in Computer Science, AI, or a related field or equivalent industry experience Strong background in Python or similar languages Significant experience with backend development , microservices, and distributed systems Hands-on experience with AI/ML systems , including LLMs, RAG, or vector databases Solid understanding of containerisation and orchestration (Docker / Kubernetes) Experience delivering secure, on-premise or regulated systems Proven ability to lead technically , mentor others, and take ownership of complex problems

Desirable Experience in defence, government, healthcare, or other regulated domains Familiarity with Dev Ops practices, CI/CD pipelines, and infrastructure as code Exposure to data engineering, ETL pipelines, or high-volume data processing Experience working in SME or start-up environments , comfortable wearing multiple hats Salary: £90,000 - £100,000 (DOE)  Bonus  Benefits Hybrid working 1 day per week onsite in either Winchester/Basingstoke