Defence Account Director

Cosine; Greater London; On-site; GBP 120,000 - 180,000; Full time

Job summary

Cosine in London is seeking a Defence Account Director to shape and own the defence opportunity strategy, building senior relationships across the MOD and defence industry. You will translate customer needs into credible use cases, pilots and programmes, leading opportunities from dialogue to delivery.

The role requires deep understanding of Defence workflows, procurement and technology adoption, with the ability to navigate long sales cycles while maintaining urgency and focus.

Qualifications

• Experience within the UK Defence ecosystem and understanding of its procurement channels.
• Ability to build trusted relationships with Defence, Government and industry.
• Experience introducing or adopting complex technology.
• Strong commercial judgement and accountability for pipeline and revenue.
• Ability to structure ambiguous problems into actionable opportunities.

Responsibilities

• Build and own a prioritised Defence account and opportunity strategy.
• Develop trusted relationships with senior stakeholders across the MOD, Front Line Commands, Government and defence industry.
• Identify operational problems, programmes and capability gaps where Cosine can make a material difference.
• Translate customer needs into clearly defined use cases, propositions, pilots and programmes.
• Navigate Defence stakeholders, budgets, acquisition routes, procurement processes and decision-making structures.
• Lead opportunities from initial conversation through demonstration, evaluation, commercial agreement and delivery.
• Collaborate with Cosine's technical teams to create credible customer propositions.
• Develop relationships with primes, strategic partners and technology companies to strengthen route to market.
• Maintain disciplined account planning, pipeline management, qualification and forecasting.

Skills

UK Defence ecosystem

Stakeholder engagement

Complex technology

Commercial judgement

Pipeline management

Defence relationships

Strategic account planning

Job description

Job Title: Defence Account Director

Location: London; full in-office working as default

Start date: ASAP

Reports to: CCO

Compensation: Salary and Equity options available for discussion

Clearance: Must be eligible to hold UK Security Vetting Clearance SC or above (no prior clearance required)

Application deadline: 01/11/26 at 23:59 UK time

Help make sovereign AI operational for UK Defence

Cosine is a UK AI lab building models, applications and infrastructure for mission-critical organisations.

We build coding agents, specialised Lumen models, AI-native security products and the infrastructure required to deploy advanced AI in demanding environments. We are also training Lumen Sovereign, the first frontier large language model trained in the UK, with the support of the UK Government.

Defence is a strategic priority for Cosine.

AI will change how Defence operates, from software engineering and intelligence analysis to cyber security, command and control, logistics and frontline operations. The challenge is turning advanced AI into capability that is trusted, secure, sovereign and useful in the real world.

We are looking for a Defence Account Director to help build that business.

This is not a traditional defence sales role. You will understand where Cosine can make a genuine operational difference, identify the right customers and programmes, shape credible opportunities and help turn early conversations into funded pilots, programmes and long-term customer relationships.

You will work closely with Cosine's Defence Lead, technical teams and senior leadership. You will build relationships across the MOD, the Armed Forces, wider Government and the UK defence industry, while helping define Cosine's position in the emerging sovereign AI market.

What you'll do

• Build and own a prioritised Defence account and opportunity strategy.
• Develop trusted relationships with senior stakeholders across the MOD, Front Line Commands, wider Government and defence industry.
• Identify operational problems, programmes and capability gaps where Cosine can make a material difference.
• Translate customer needs into clearly defined use cases, propositions, pilots and programmes.
• Navigate Defence stakeholders, budgets, acquisition routes, procurement processes and decision-making structures.
• Lead opportunities from initial conversation through demonstration, technical evaluation, commercial agreement and delivery.
• Work with Cosine's technical teams to create credible customer propositions without overpromising.
• Develop relationships with primes, strategic partners and specialist technology companies where this creates a stronger route to market.
• Maintain disciplined account planning, pipeline management, qualification and forecasting.
• Bring structured customer and market insight back to Product, Engineering, ML and senior leadership.

What we're looking for

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. What matters is that you understand how Defence works and can turn a customer need into commercial momentum.

You should have:

• Meaningful experience of the UK Defence ecosystem.
• Strong existing relationships across Defence, Government or industry, and the ability to build new ones.
• Experience introducing, acquiring or adopting complex technology.
• The ability to structure ambiguous problems and turn them into actionable opportunities.
• Strong commercial judgement and comfort being accountable for pipeline, opportunities and revenue.
• The confidence to engage with operators, engineers, procurement teams, senior civil servants, military leaders and industry executives.
• Genuine technical curiosity and the ability to learn enough about AI to have credible conversations with technical teams and customers.
• The resilience to work through long Defence sales cycles while maintaining urgency and focus.
• The independence and judgement to operate in a scale-up where the playbook is still being written.

You do not need to be an AI expert when you join. You do need to be intellectually curious, technically literate and able to communicate clearly without hiding behind jargon.

What success looks like

Success ultimately means winning business and building enduring customer relationships. We aim to onboard at least 10 new client logos within the Defence account over the next 12 months and increase revenues by at least 300%. We expect that growth to come through credibility, judgement, customer insight and persisten