Founding Head of Public Sector

Job title: Founding Head of Public Sector

Location: London; 4 days in-office, 1 day wfh

Reports to: Chief Commercial Officer

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Cosine is the UK's frontier AI lab for autonomous software engineering — not another coding assistant, but our own models, agent stack, eval harnesses, and product layer. We build our agent tooling entirely in-house and post-train open-source models to deliver reliable, enterprise-grade coding performance in security-critical settings.

Our offerings can be used as SaaS, deployed on VPC, on-prem or fully air-gapped. Through this flexability, we are able to service large-scale, highly regulated enterprises and industries including defence, financial service and healthcare.

We’re backed by YC and were recently selected for the UK’s sovereign AI programme. The company is at a rare stage: deep technical work, real enterprise pull, and a chance to shape how AI is deployed inside defence, banking, government, and other high-trust environments.

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Own Cosine’s public sector engagement and GTM motion from founder-led relationship building into a repeatable commercial engine.

The role exists to build on Cosine’s growing reputation across government, defence-adjacent bodies, public sector technology teams, and the wider UK sovereign AI ecosystem, turning senior interest into deep institutional relationships, clearly understood priorities, and qualified commercial opportunities.

This is a critical sector-building role: part enterprise sales, part partnerships, part market development, part public sector navigation, and part GTM leadership.

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• Own Cosine’s day-to-day engagement with priority public sector organisations, including central government departments, arm’s-length bodies, regulators, public agencies, national infrastructure bodies, and public sector technology teams.

• Build on Cosine’s growing reputation in sovereign AI, secure deployment, and trusted AI engineering to create senior routes into the right organisations.

• Maintain a clear account map across key public sector organisations, including executive sponsors, digital and technology leaders, commercial/procurement stakeholders, policy teams, risk/security owners, and delivery teams.

• Move relationships from broad sovereign AI interest into specific, practical areas where Cosine can create value.

• Develop relationships across multiple departments, divisions, seniority levels, and decision-making layers in each target account.

• Engage CIO, CTO, CISO, CDIO, digital, data, engineering, architecture, commercial, procurement, transformation, policy, security, and operational stakeholders.

• Identify how priorities differ across teams, for example secure AI deployment, software assurance, legacy modernisation, operational resilience, cost reduction, productivity, national capability, procurement risk, and governance.

• Build enough trust that Cosine becomes part of the strategic conversation around sovereign AI adoption, not just another vendor responding to tenders.

• Run structured discovery across public sector organisations to understand what they truly care about in sovereign AI.

• Capture use cases, constraints, buying triggers, objections, governance requirements, security expectations, procurement routes, deployment models, and success metrics.

• Translate public sector customer signal into internal intelligence for sales, partnerships, product, research, engineering, marketing, and leadership.

• Build a sector view of where Cosine has the strongest right to win, including priority use cases, highest-intent accounts, likely buyer personas, procurement routes, SI influence, and repeatable commercial narratives.

Priority areas to explore include:

• Secure AI coding and software engineering inside sensitive or regulated public sector environments.

• AI adoption where source code, credentials, data, or infrastructure cannot leave the customer’s control boundary.

• Legacy system modernisation and maintenance.

• Software assurance, auditability, testing, review, and governance.

• Productivity and resilience across public sector digital delivery teams.

• Deployment models across public cloud, customer VPC, on-prem, secure environments, and air-gapped environments where required.

• National capability, sovereign AI, and reducing dependency on foreign-controlled AI infrastructure.

• Convert reputation, relationship-building, and market education into qualified pipeline opportunities.

• Identify where there is a real public sector problem, accountable owner, budget route, technical champion, procurement path, and reason to act now.

• Shape opportunities into concrete next steps: workshops, technical deep-dives, discovery sessions, pilots, proof-of-concepts, deployment planning, bid participation, or commercial proposals.

• Work with the wider GTM team to move qualified public sector opportunities through the sales cycle.

• Keep a clear view of account status, stakeholder map, open actions, risks, next steps, procurement routes, SI involvement, and commercial likelihood.

The role should focus deeply on commercial pull: serious conversations, mapped accounts, live opportunities, pilots, bid routes, and ultimately revenue.

• Work alongside Cosine’s Head of Partnerships to build and manage relationships with the systems integrators, consultancies, and delivery partners that shape public sector buying.

• Identify where SIs can create routes into accounts, provide bid access, support delivery credibility, or help Cosine become part of larger transformation programmes.

• Build joint account plans with priority partners where there is a clear public sector opportunity.

• Support bid strategy, partner positioning, framework access, and teaming discussions where Cosine is best placed as a specialist sovereign AI or secure AI engineering partner.

• Ensure SI engagement is commercially purposeful, with clear ownership, target accounts, bid opportunities, and follow-up actions.

• Build a clear view of the procurement and commercial routes that matter for Cosine in public sector.

• Understand where Cosine should pursue direct engagement, partner-led opportunities, framework routes, innovation pathways, pilots, or inclusion in larger SI-led bids.

• Help shape compliant engagement approaches that create trust without relying on frequent hosted events or activity that could create procurement issues.

• Use targeted briefings, structured discovery, partner conversations, written materials, and appropriate market engagement routes to progress opportunities.

• Work with legal, commercial, partnerships, and leadership to ensure public sector engagement is commercially useful and procurement-aware.

• Help define what the public sector GTM motion should become as Cosine scales.

• Build the early playbook for account selection, stakeholder mapping, discovery, qualification, partner-led entry, SI engagement, bid strategy, pilot design, procurement navigation, and commercial progression.

• Help recruit, onboard, and develop future GTM hires focused on public sector.

• Establish the operating cadence for the sector: account reviews, pipeline tracking, partner follow-up, bid tracking, customer insight capture, and internal reporting.

• Work closely with SDRs, partnerships, marketing, founders, enterprise sales, and the Head of Partnerships to make public sector a repeatable vertical.

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• Multi-threaded relationships established across the most important public sector accounts.

• The three top priority public sector accounts are established, with account maps, stakeholder coverage, routes to procurement, partner/SI strategy, and business cases set out.

• A structured view of public sector sovereign AI use cases, buyer priorities, objections, procurement routes, SI influence, and buying triggers.

• Qualified opportunities progressing into discovery, technical deep-dives, pilots, bid discussions, partner motions, or commercial proposals.

• Clear working rhythm with the Head of Partnerships on SI engagement, bid routes, partner mapping, and public sector account strategy.

• A clear public sector GTM playbook that future hires can build from.

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• Number of priority public sector accounts actively engaged.

• Number of senior stakeholder relationships built across target accounts.

• Number of multi-threaded accounts with executive, technical, commercial, procurement, and partner coverage.

• Quality of customer insight captured on sovereign AI priorities, deployment requirements, procurement constraints, and use cases.

• Qualified public sector opportunities created.

• Workshops, technical deep-dives, pilots, bid discussions, partner motions, or proposals initiated.

• Pipeline generated or influenced.

• Conversion of reputation and senior engagement into live commercial next steps.

• Evidence that Cosine is becoming a serious strategic partner in target public sector accounts.

• Priority SI and consultancy relationships mapped and actively managed alongside the Head of Partnerships.

• Joint account plans created with the most relevant partners.

• Bid opportunities, framework routes, or partner-led entry points identified.

• Clear evidence that partner engagement is creating access, credibility, or commercial opportunity.

• Public sector account map and stakeholder tracker built and maintained.

• Partner/SI map built and maintained with clear ownership and next steps.

• Repeatable cadence established for account reviews, partner follow-up, bid tracking, and sector reporting.

• Future public sector GTM hiring profile defined.

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Cosine will support the role with:

• Founder access for senior meetings and strategic accounts.

• Existing reputation, warm routes, and credibility from Cosine’s sovereign AI work.

• Support from the Head of Partnerships on SI engagement, partner strategy, bid routes, and partner-led account entry.

• Support from partnerships, marketing, product, engineering, ML, and legal where needed.

• Enterprise-grade materials on sovereign AI, deployment models, security, product architecture, public sector use cases, and ROI.

• Budget for targeted customer and partner engagement where appropriate and compliant.

• Clear internal ownership for technical escalation, pilot scoping, legal/procurement, bid support, and product feedback.

• A single accountable line manager for commercial direction and prioritisation.

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This role is likely to suit someone who:

• Has sold, partnered, or built relationships inside public sector, government, regulated infrastructure, defence-adjacent markets, or public sector technology programmes.

• Understands how public sector organisations buy, including procurement routes, framework dynamics, bid processes, partner influence, and the role of SIs.

• Can credibly engage senior stakeholders while still doing the account-by-account follow-up work themselves.

• Understands complex enterprise and public sector buying cycles and knows how to move from relationship to qualified opportunity.

• Is comfortable working with SIs, consultancies, and delivery partners without losing sight of Cosine’s own commercial interest.

• Is procurement-aware and knows how to build trust in public sector without relying on heavy entertainment, excessive events, or informal routes that may create issues later.

• Is comfortable with ambiguity, sector-building, and founder-led GTM rather than inheriting a mature sales machine.

• Thinks commercially, writes clearly, and can build account plans, briefing notes, proposals, bid inputs, and internal decision materials without heavy supervision.

• Has the judgement to know when a conversation is just interesting and when it is becoming real pipeline.

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The Founding Head of Public Sector should make Cosine impossible to ignore for the right public sector organisations.

They should build on Cosine’s growing reputation in sovereign AI, understand what these institutions actually need, build the relationships required to be taken seriously, and work closely with systems integrators and the Head of Partnerships to create credible routes into bids and programmes.

Over time, they should turn that trust into qualified commercial opportunities, while building the team, playbook, partner motion, procurement discipline, and operating cadence that make public sector a repeatable Cosine vertical rather than a founder-led experiment.

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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

• 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

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

  • Dog-friendly office - bring your dog to work

  • Weekly team breakfast & lunch

  • Monthly socials

  • Pension

  • High-quality equipment to do your best work

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We’re an equal opportunity employer. We value diverse backgrounds and encourage applications from everyone who meets the role requirements, even if you don’t tick every box.