Job Description

Job title:

Enterprise Account Executive (Defence)

Location:

London; full in-office working as default

Start date:

ASAP

Reports to:

CRO

Compensation:

75k-125k base plus commission and equity


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Cosine at a glance

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At Cosine, we're building agentic AI systems designed to take real action in the world.


We're not a chatbot or a thin wrapper around existing models. Our systems are built to run in on-premises, closed-loop environments, including fully air-gapped deployments, where reliability and control matter.


In 2024, Cosine achieved a 72% score on OpenAI's SWE-Lancer benchmark, placing us among the strongest real-world software-engineering AI systems evaluated.


YC-backed and well-funded, Cosine was founded by experienced operators focused on building dependable, production-grade AI.

This role is based in our Hoxton office, five days a week, because close collaboration, fast feedback, and shared context matter for the problems we're solving.

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The role

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As an Enterprise Account Executive for Defence, you will own and close complex enterprise deals across defence primes, government agencies, and national security organisations. You will navigate highly regulated procurement environments and work closely with senior technical, security, and programme stakeholders to turn pilots into long-term production deployments.


This role is ideal for someone who has successfully hunted and closed new logo enterprise deals within defence or government, particularly selling developer tooling, infrastructure, security, or platform technologies into mission-critical engineering teams.


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What you'll do

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Own the full sales cycle across defence and government accounts, from targeted outbound and partner-led sourcing through to close Hunt and develop new defence opportunities, including direct relationships with defence primes, government departments, and classified programme teams Lead complex, multi-stakeholder sales processes involving engineering leadership, security, procurement, and programme owners Design and manage pilots and technical evaluations, defining success criteria aligned to mission outcomes, security constraints, and operational readiness Build deal strategies that account for long procurement timelines, framework agreements, and partner ecosystems Work closely with product, engineering, and leadership to shape Cosine's defence positioning, deployment models, and roadmap priorities Help formalise Cosine's defence go-to-market playbook, including qualification, pilot structures, accreditation pathways, and scale-out strategies Maintain rigorous pipeline management, forecasting, and CRM hygiene across long-cycle opportunities

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What we're looking for

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A demonstrated track record of closing complex enterprise deals within defence, government, or national security environments Experience selling developer tooling, infrastructure, security, or data platforms into large, technically sophisticated organisations Background at, or selling products comparable to, companies such as AWS, Kubernetes, Terraform, GitHub, Datadog, Grafana, Cloudflare, GCP, or similar developer-first or infrastructure platforms Strong understanding of defence and government procurement processes, including frameworks, primes, and compliance requirements Credibility engaging with senior technical, security, and programme stakeholders in high-assurance environments Comfort operating in environments with long sales cycles, multiple decision-makers, and strict security constraints Strong written and verbal communication skills, with the ability to communicate complex technical concepts clearly to both technical and non-technical audiences

Nice to have

Experience selling on-premise, air-gapped, or classified systems Familiarity with defence primes, systems integrators, or government procurement frameworks Exposure to AI, ML platforms, or developer productivity tooling Existing network within defence, government, or national security technology organisations

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Why join Cosine

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Opportunity to sell a

genuinely differentiated product

into mission-critical defence and national security environments

Meaningful early equity

with real upside

Direct impact

on product direction and go-to-market strategy

Small, elite team

with high standards and strong technical depth

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Cosine is an equal opportunity employer.

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We value diverse backgrounds, perspectives, and ways of thinking, and we're committed to creating an inclusive and respectful workplace.


We encourage applications from anyone who meets the role requirements, even if you don't meet every single qualification. If you need reasonable adjustments at any stage of the hiring process, we're happy to discuss them.


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Compensation, Benefits & Ways of Working

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We're an in-office team, five days a week, by design. We believe the work we're doing benefits from being together, collaborating closely, and building shared context.

What you can expect:

Competitive salary

, benchmarked to the market

Equity / share options

, so you share in the upside you help create

30 days' holiday + bank holidays

Genuine 9-5 working hours

-- we don't expect late nights or weekend work

Work hard in the office, collaborate closely, and switch off properly

Dog-friendly office

-- bring your dog to work

Daily lunch provided

Monthly team breakfasts

Monthly socials

Pension

High-quality equipment

to do your best work

We care about focus, sustainability, and doing great work -- not performative overwork. We value people who show up, contribute thoughtfully, collaborate well with their colleagues, and then go home.


This role won't suit everyone. But if you want structure, clarity, strong collaboration, and a team that takes both the work and work-life balance seriously, it's a great place to be.


Compensation Range: 75K - 125K