Principal Site Reliability Engineer x5 (SC Cleared)

Principal Site Reliability Engineer x5 (SC Cleared) South England - hybrid working - £70,000 - £90,000 + perm benefits We are seeking experienced Principal Site Reliability Engineers (SRE) to join a high-performing engineering team delivering resilient, cloud-native platforms for UK-based customers. These roles blend senior technical leadership with hands-on delivery, covering both project-based work and the ongoing reliability, scalability, and security of critical services. You'll work closely with other senior engineers in small, collaborative teams, taking ownership of platform reliability, setting best practices, and mentoring others. The role supports critical national infrastructure, requires participation in an on-call rota, and operates within a hybrid working model across UK offices, client sites, and home. Key responsibilities Design, build, and maintain highly available, scalable, and resilient platforms, prioritising standardisation, reuse, and automation Champion GitOps-first approaches, minimising manual configuration ("ClickOps") Lead and contribute to Site Reliability Engineering practices, including error budgets, SLOs, SLIs, and incident management Work in agile delivery teams, aligning engineering outcomes to customer and service reliability goals Operate within defined on-call rotas, supporting services underpinning critical national infrastructure Provide technical leadership and mentorship, developing the capability of engineers across teams Promote and embed best practices in reliability, security, observability, and automation Contribute to the evolution of cloud-native and SRE standards, patterns, and platform strategiesSkills and experience Proven leadership experience in Site Reliability Engineering or senior platform engineering roles Strong expertise in Kubernetes and OpenShift (CKA/CKS certifications beneficial) Experience designing complex multi-cloud or hybrid architectures Hands-on knowledge of service mesh technologies such as Istio Experience with enterprise-grade databases, including EDB Postgres Deep understanding of observability and monitoring stacks, such as Prometheus, Grafana, Loki, Tempo, and LogiStack Strong Infrastructure as Code experience using tools such as Helm or Kustomize Proficiency in scripting and automation, including Bash and Python CI/CD and GitOps pipeline management using tools such as ArgoCD, FluxCD, or Tekton Experience with Red Hat ACM/ACS and advanced container networking (e.g. Submariner) A strong focus on reliability, automation, and operational excellence