Founding Head of Public Sector at Cosine.sh

Job Title

Founding Head of Public Sector

Not Disclosed

Cosine.sh is a YC-backed UK frontier AI lab for autonomous software engineering that was recently selected for the UK’s sovereign AI programme alongside partners like BAE Systems, Babcock, and the Alan Turing Institute.

You will lead Cosine.sh's public sector GTM strategy, transforming deep technical innovation into a repeatable commercial engine. As a founding leader, you'll navigate complex procurement routes, build high-trust relationships within UK government and defense, and scale a vertical that deploys secure, autonomous AI engineering inside high-trust, security-critical environments.

London, UK

• Direct participation in the UK's sovereign AI programme, Lumen Sovereign, working alongside giants like BAE Systems, Thales UK, and the Alan Turing Institute.
• A founding-level leadership position where you shape the GTM playbook for security-critical AI deployment in government, defense, and national security sectors.
• Exceptional technical leverage—selling proprietary models and an agent stack designed for air-gapped and on-premise environments where generic AI assistants cannot operate.

• Own and execute the end-to-end engagement strategy for central government departments, defense-adjacent bodies, and national infrastructure organizations.
• Build multi-threaded relationships with CIOs, CDIOs, and security stakeholders to move from general AI interest to specific, high-value commercial opportunities.
• Collaborate with elite systems integrators and delivery partners to navigate procurement frameworks and secure inclusion in large-scale public sector transformation programs.

• Proven experience building public-sector GTM motions at high-growth UK tech scale-ups or leading government-focused sales at major global consultancies.
• Deep understanding of UK public sector procurement, framework dynamics, and the specific security constraints of defense and national security environments.
• A builder mindset capable of hands-on deal execution while simultaneously designing the long-term strategy and recruitment plan for the public sector vertical.