Principle IT Security Specialist - London - Hybrid Working £80,000 - £105,000 (dependent on experience) Equity & Benefits Help Build Europe's Hypersonic Capability This organisation is redefining what's possible in European defence technology, delivering speed, resilience, and technological independence at a pace that sets a new standard. Operating as a small, elite, and highly capable team, it focuses on solving complex, high-impact problems quickly and effectively. They are seeking an Lead IT Security Specialist to join a talent-dense environment where every individual plays a critical role in shaping both technical direction and organisational capability. This is not a predefined role, it is an opportunity for a high-calibre security professional to take ownership of core security functions, with scope to evolve the position based on their strengths and expertise. The successful candidate will play a key role in strengthening security posture through SIEM ownership, incident response, and system hardening, directly contributing to Europe's technological sovereignty. The Role The IT Security Specialist will: Design, build, and operate a centralised SIEM platform to aggregate and analyse security logs across infrastructure, networks, and applications Own security log analysis, vulnerability management, and incident investigation, including defining baselines and developing alerting rules for critical events Lead incident response efforts, using log correlation and analysis to investigate and resolve security issues quickly and effectively Define and implement system and application hardening standards, ensuring strong, consistent security configurations across environments Act as an on-call responder for security incidents, taking full ownership from detection through to resolution and post-incident improvement Collaborate with Information Security and leadership teams to ensure compliance with relevant standards and frameworks (e.g. Cyber Essentials, ISO 27001, DEF STAN, Grundschutz) Develop and maintain clear documentation covering SIEM architecture, security controls, incident response procedures, and audit requirements Candidate Profile The ideal candidate will bring: Hands-on experience deploying and operating SIEM solutions (e.g. ELK Stack, OpenSearch, Wazuh, Microsoft Defender), with proven incident investigation experience in production environments Strong expertise in Linux and Windows system hardening, with familiarity across frameworks such as CIS Benchmarks or STIGs Scripting capability for automation, log parsing, and alerting rule development Experience working within compliance-driven or regulated environments A strong security mindset, with a focus on access control, threat detection, and auditability The ability to balance robust security controls with operational efficiency High levels of autonomy and sound judgement, with the ability to manage incidents end-to-end A pragmatic, delivery-focused approach, prioritising effective security outcomes over theoretical perfection Security Clearance Due to the nature of the work, applicants must be British citizens (or dual nationals with British citizenship) and eligible for UK Security Clearance (SC), with the potential requirement for Developed Vetting (DV). What's on Offer The opportunity to work on one of Europe's most critical and high-impact defence challenges A high-autonomy environment with full ownership of key security capabilities Collaboration with leading experts across engineering, operations, and defence A fast-paced setting where ideas are implemented quickly and security improvements have immediate impact A culture built on clarity, integrity, and excellence, supporting individuals who take initiative and operate with accountability Competitive compensation and meaningful equity aligned to impact and responsibility Robert Half Ltd acts as an employment business for temporary positions and an employment agency for permanent positions. Robert Half is committed to diversity, equity and inclusion. Suitable candidates with equivalent qualifications and more or less experience can apply. Rates of pay and salary ranges are dependent upon your experience, qualifications and training. If you wish to apply, please read our Privacy Notice describing how we may process, disclose and store your personal data: roberthalf.com/gb/en/privacy-notice.