Senior Security Engineer - Detection Engineering in Welwyn Garden City

As a Senior Security Engineer in Tesco’s Detection Engineering team, you will lead the technical design of security‑first infrastructure and deliver high‑impact engineering outcomes that protect a global retail ecosystem serving millions of customers. You will translate complex threat and risk signals into resilient, testable, and automated security capabilities across Tesco’s technology landscape. The role blends deep engineering leadership with a customer‑first mindset – preventing disruption, safeguarding trust, and raising the bar on engineering quality across cyber defence. You will also mentor engineers and help shape an innovation agenda that strengthens Tesco’s ability to detect and withstand sophisticated cyber threats.

You will be responsible for:

• Designing, building and deploying complex, high‑reliability security capabilities that offer proactive visibility into Tesco’s estate and materially reduce risk to customer services and operational continuity.
• Championing secure, test‑driven engineering, including code quality, automated testing, peer review and repeatable delivery practices across the team.
• Identifying opportunities and piloting AI‑assisted and automation‑driven approaches that improve detection lifecycle effectiveness, ensuring changes deliver measurable improvements rather than novelty.
• Coaching and supporting junior engineers, building confidence in modern development practices, problem‑solving, and pragmatic security design decisions.
• Working seamlessly with Security Operations, Threat Intelligence, platform teams and product/engineering stakeholders to deliver integrated defences—communicating clearly, influencing effectively, and fostering an inclusive, high‑performing culture.

You will need:

• Demonstrated ability to deliver production‑grade solutions safely, from design through build, test, deploy, operate and improve.
• Evidence of writing clean, maintainable code or scripts and applying appropriate patterns for reliability, scalability and operational support.
• Evidence of having developed custom detections and working with data at scale in products.
• Knowledge of threat‑aware design, secure defaults, automated tests and disciplined change control, and how these practices raise the quality bar across a team.
• Understanding of how detection and response outcomes are underpinned – e.g., telemetry sources, detection platforms, triage workflows and response integration.
• Fundamentals at scale – converting hypotheses about adversary behaviour into effective detections, reducing noise without impacting visibility, and sustaining quality over time.
• Evidence of curiosity, continuous learning and proactive professional development, including sharing knowledge and improving team practice.
• Proven ability to foster an environment where diverse perspectives are welcomed, engineers are supported, and collaboration is the default.
• Exposure to evaluating emerging techniques (including AI‑assisted approaches) with sound judgement – balancing value, safety and operational reality.

Desirable:

• Exposure to a core technology landscape and strong retail technology awareness, including how customer journeys and store/online operations shape risk.
• Demonstrable understanding of security evaluation and functionality testing, including validating controls and detections against expected outcomes.
• Cloud & container security knowledge, including common control patterns and engineering approaches to hardening cloud‑native services.
• Applied AI for cyber defence familiarity, and awareness of AI governance / responsible AI considerations.
• Strong research habits and data‑informed decision making.
• Experience working with delivery and operational tooling such as GitHub & Jira, and incident collaboration tooling such as Zendesk & xMatters.
• Experience with a querying language such as SPL, KQL, SQL etc. in a Security Environment.
• Communication and influencing skills across engineering, product and security stakeholders; comfort guiding decisions under ambiguity and driving change.
• Familiarity with product methodologies and security architecture concepts to help shape “secure‑by‑design” outcomes across teams.

Benefits:

• Annual bonus scheme of up to 20% of base salary.
• Holiday starting at 25 days plus a personal day (plus bank holidays).
• Private medical insurance.
• 26 weeks maternity and adoption leave at full pay, followed by 13 weeks of Statutory Maternity Pay or Statutory Adoption Pay; we also offer 6 weeks fully paid paternity leave.
• Free 24/7 virtual GP service, Employee Assistance Programme (EAP) for you and your family, free access to a range of experts to support your mental wellbeing.

This information is a shortened summary; refer to our policies for full details.

We’re proud to be an accredited Disability Confident Leader. We always welcome a conversation about flexible working, so talk to us throughout your application about how we can support.