SlipstreamJobs tracks this role from the company's public career site. Apply directly on the employer's site.
Cosine is a UK AI lab building models, applications and infrastructure for mission-critical organisations, including coding agents, specialised Lumen models, AI-native security products, and deployment infrastructure for advanced AI in demanding environments. The company is training Lumen Sovereign, the first frontier large language model trained in the UK with UK Government support. Defence is a strategic priority.
This Defence Account Director role is not a traditional defence sales position. You will identify where Cosine can make genuine operational difference, find the right customers and programmes, shape credible opportunities, and convert early conversations into funded pilots, programmes and long-term relationships. You will work closely with Cosine's Defence Lead, technical teams and senior leadership, building relationships across the MOD, Armed Forces, wider Government and UK defence industry while helping define Cosine's position in the sovereign AI market.
Key responsibilities include: building and owning a prioritised Defence account and opportunity strategy; developing trusted relationships with senior stakeholders across MOD, Front Line Commands, Government and defence industry; identifying operational problems and capability gaps where Cosine can make material difference; translating customer needs into use cases, propositions, pilots and programmes; navigating Defence stakeholders, budgets, acquisition routes and procurement processes; leading opportunities from initial conversation through demonstration, evaluation, commercial agreement and delivery; working with technical teams to create credible propositions; developing relationships with primes and strategic partners; maintaining disciplined account planning, pipeline management and forecasting; and bringing structured customer and market insight to Product, Engineering, ML and leadership.
Success means winning business and building enduring customer relationships. The company aims to onboard at least 10 new client logos within the Defence account over 12 months and increase revenues by at least 300%, driven by credibility, judgement, customer insight and persistence rather than transactional selling.
In the first few months you will build a clear view of Cosine's Defence proposition and priorities, establish a focused account and stakeholder map, develop relationships with priority customers and partners, identify and qualify promising opportunities, and create a disciplined approach to account planning and forecasting.
The role reports to the Chief Commercial Officer and requires full in-office working in London (five days per week). Start date is ASAP with an application deadline of 01/11/26.
REQUIREMENTS:
- Meaningful experience of the UK Defence ecosystem
- Strong existing relationships across Defence, Government or industry, with ability to build new ones
- Experience introducing, acquiring or adopting complex technology
- Ability to structure ambiguous problems and turn them into actionable opportunities
- Strong commercial judgement and accountability for pipeline, opportunities and revenue
- Confidence engaging with operators, engineers, procurement teams, senior civil servants, military leaders and industry executives
- Genuine technical curiosity and ability to learn enough about AI for credible conversations with technical teams and customers
- Resilience to work through long Defence sales cycles while maintaining urgency and focus
- Independence and judgement to operate in a scale-up environment
- Must be eligible to hold UK Security Vetting Clearance SC or above (no prior clearance required)
Background: You may have served in the UK Armed Forces or worked closely with Defence in engineering, capability development, acquisition, procurement, digital transformation or technology adoption. You may subsequently have worked in consulting, technology, industry or an advisory role. You do not need to be an AI expert when you join, but you must be intellectually curious, technically literate and able to communicate clearly without hiding behind jargon.
