Head of Security/Security Lead - Fintech Unicorn | London (FTE) A high-growth fintech unicorn is seeking a Head of Security/Security Lead to join its London office. This pivotal role reports directly to the CTO and is responsible for shaping the company's security vision, building a robust technical roadmap, and leading a team of engineers in implementing and automating cutting-edge security controls across cloud infrastructure, application security, and threat detection. This is a hands-on leadership role. While strategic oversight is key, the successful candidate will also be expected to contribute technically-writing code and solving complex problems alongside the team when needed. Key Responsibilities Strategic Leadership Define a multi-year security engineering strategy aligned with business risk appetite and regulatory requirements. Drive high-impact initiatives including infrastructure hardening, application security, threat detection and response, and digital asset protection. Team Development & Mentorship Build, lead, and nurture a high-performing security engineering team. Set clear objectives, performance metrics, and career development plans. Architecture & Engineering Oversight Design secure-by-default patterns for AWS, Kubernetes, CI/CD pipelines, and digital asset custody. Conduct threat modeling for distributed systems and approve mitigation strategies. Automation & Scalability Lead efforts to automate vulnerability discovery, measurement, and contextualization. Minimize manual processes using Python tooling and Infrastructure-as-Code (IaC) scanning. Cross-Functional Collaboration Act as the primary bridge between Security, Engineering, Operations, and IT. Embed security requirements early in product development and support teams throughout delivery. Research & Threat Intelligence Stay ahead of emerging threats such as DeFi exploits and cloud privilege escalation. Translate research into actionable controls and incident response playbooks. Governance & Incident Preparedness Develop and test incident response procedures; ensure 24/7 detection coverage. Present security posture, metrics, and strategic plans to executive leadership. Required Qualifications 10 years in security engineering, including 3 years leading high-performing teams in fintech, exchanges, or large-scale web environments. Deep expertise in one or more domains: cloud/infrastructure hardening, application security, detection engineering, or crypto security. Proven experience deploying automated security pipelines (e.g., IaC scanning, secret detection, exploit simulation). Proficiency in modern programming languages (Python, Go, Rust) and familiarity with microservices and distributed systems. Experience conducting threat modeling for high-value, low-latency trading or custody platforms. Strong communication skills with the ability to translate technical risks into business impact. Preferred Qualifications Leadership experience in financial institutions, broker-dealers, or regulated digital asset platforms. Knowledge of custody models, MPC wallets, or DeFi smart contract risks. Advanced degree in Computer Science, Information Security, or a related field.