Applied ML Technical Lead, Defence
Overview
Cosine is a UK AI lab building models, applications and training infrastructure for mission-critical organisations, including coding agents, specialised Lumen models and AI-native security products. It is also training Lumen Sovereign, described as the first frontier large language model trained in the UK, with UK Government support. The company is hiring a full-time Applied ML Technical Lead for Defence in London, working full time in the office by default, reporting to the CEO and starting as soon as possible.
The role is hands-on technical leadership across machine learning development, deployment and customer-facing delivery for UK Defence and national security organisations. It is not a traditional project management post: the lead owns technical direction and day-to-day progress, coordinating the people and decisions needed to turn research into operational capability.
Work includes designing, training and evaluating models for applied Defence use cases involving complex sensor data, signal processing, pattern recognition and multimodal intelligence, improving architectures, training pipelines and inference systems, and using real-world and synthetic datasets. The lead turns operational objectives into technical goals, experiments and milestones, identifies risks and blockers, and sets evaluation criteria. They engage directly with Defence stakeholders, present progress to technical and non-technical audiences, and help customers understand deployment, including secure, on-premise and resource-constrained environments, with attention to optimisation, performance, reliability and feedback loops.
Requirements
Cosine expects a background in applied machine learning, ML engineering or research engineering with experience owning complex technical work. Candidates should write production-quality Python, use frameworks such as PyTorch, train and evaluate models, work with complex datasets, understand trade-offs between performance, compute, latency and deployment constraints, and use Git, containers, Linux and GPU compute. Prior Defence experience is not required. Existing UK security clearance, signal processing or sensor fusion experience, foundation model or multimodal experience, edge deployment, familiarity with UK Defence procurement and experience leading technical workstreams are advantages. In the first three months the lead is expected to become technical lead for a major applied Defence ML programme.
Who can apply
Applicants must be eligible to hold UK Security Vetting clearance at SC level or above, and no prior clearance is required. Visa sponsorship is available for suitable candidates. Compensation is salary and equity options, available for discussion.
Key dates
The application deadline is 8 November 2026 at 23:59 UK time.