Location
Central London

Hours
Full Time

Salary
£44,190 to £52,972 depending on skills and accreditation

About the Role
MI5 keeps the country safe from serious threats like terrorism and attempts by states to harm the UK, its people and way of life. We carry out investigations by obtaining, analysing, and assessing intelligence, and then work with a range of partners including MI6 and GCHQ to disrupt these threats. Through our protective security arm, we provide advice and guidance to government, businesses and other organisations about how to keep themselves safe. A role in MI5 means you'll do unique and challenging work in a supportive and encouraging environment, making a real difference to UK national security.

As a Site Reliability Engineer, you’ll design, build, deploy and maintain the infrastructure that enables critical cyber activity. Working in a highly technical environment, you’ll ensure the systems others depend on are secure, reliable and fit for purpose. Using a blend of cutting-edge and bespoke technologies, including internally developed systems you won’t find elsewhere, you’ll solve complex, mission-critical challenges.

This is an engineering-led role where you’ll play a key part in delivering and managing infrastructure through code, operating in fully code-driven environments. Using tools such as Kubernetes, infrastructure as code and automation frameworks, you’ll develop and manage production environments that support operational activity. You’ll oversee deployments end to end, manage upgrades and changes, and ensure systems remain stable and available without disruption, maintaining continuity of service.

Monitoring is central to the role. You’ll track system health, performance and behaviour using logs and metrics, identifying risks and weaknesses before they impact service. When issues arise, you’ll investigate root causes and contribute to improvements that strengthen reliability and prevent recurrence.

Day to day, you’ll work closely with engineers, developers and researchers to deploy new capabilities and improve existing systems. You’ll collaborate with monitoring teams to respond to system concerns and ensure environments remain secure and resilient. Alongside this, you’ll contribute to improving how systems are managed, refining processes and strengthening reliability practices as systems evolve.

Operating within a small, specialist team in a wider delivery environment, you’ll have the autonomy to influence how production systems are managed and delivered. This is a hands-on engineering role focused on ensuring systems are robust, consistently available and capable of supporting critical operational activity.

Benefits
When you join, you’ll receive an induction to the team, systems and ways of working, helping you understand how the infrastructure you support fits into the wider operational environment. Your personal development in this role is continuous and grounded in practice. You’ll build your expertise by working directly with complex systems, contributing to deployments, monitoring environments and responding to real-world challenges. Alongside this, you’ll have dedicated time to explore emerging technologies, keeping your skills current and identifying opportunities to improve future capability.

You’ll be supported through a structured technical framework aligned to the Cyber Technical Framework, helping you progress as a specialist engineer or move into leadership. Whichever path you choose, you’ll receive significant investment in your development, including funded external courses, certifications and technical bootcamps.

You’ll also have access to a Dedicated Development Budget and Personal Development Time, giving you the flexibility to pursue self-directed learning aligned to your goals. Opportunities to gain industry-recognised certifications and learn from leading specialists across the intelligence community will further support your development.

Rewards and Benefits
25 Days Annual Leave automatically rising to 30 days after 5 years' service, and an additional 10.5 days public and privilege holidays
Opportunities to be recognised through our employee performance scheme
Dedicated development budget
Interest-free season ticket loan
Excellent pension scheme
Cycle to work scheme
Facilities such as a gym, restaurant, and on-site coffee bars (at some locations)
Paid parental and adoption leave

Experience
You’re an experienced engineer with a strong background in building, deploying and maintaining software or infrastructure in production environments. Your experience may come from site reliability engineering, DevOps or a similar role, and you’ll be used to working with complex systems where reliability, performance and security are critical. You bring hands-on experience managing systems through their full lifecycle, including deploying, upgrading and maintaining services in live environments without disruption. You’re confident working in code-driven environments, using approaches such as infrastructure as code and automation to deliver and manage infrastructure.

You’ll have practical experience using Kubernetes to deploy and manage services in production environments. You’ll also have working knowledge of scripting or programming languages such as Python and be comfortable working in Linux-based environments.

You understand how systems behave in production, using logs, metrics and monitoring tools to assess health, identify issues and improve performance. You take a structured and methodical approach to your work, ensuring systems are stable, repeatable and well managed.

You’re able to understand complex systems and how different components interact and can communicate this clearly to others. You work effectively with engineers and supporting teams, ensuring systems are well documented and delivered to a consistent standard.

About you
You are methodical, proactive and collaborative, with a strong commitment to maintaining system reliability and security. You thrive in a fast-paced, mission-critical environment and are motivated by the opportunity to contribute to national security through your technical expertise.

Qualifications
Relevant technical qualifications or certifications are desirable but not essential. A commitment to continuous professional development and learning is expected, supported by the structured technical framework and development opportunities provided.