Senior Infrastructure Engineer

Work on Technology That Protects What Matters

At SiXworks, we build secure digital solutions that support Defence and National Security missions. Our teams work on complex problems where reliability, security, and speed of innovation matter.

We’re looking for a Senior Infrastructure Engineer who enjoys solving difficult technical challenges and wants their work to have real operational impact.

This role requires the highest level of UK security clearance.

What You’ll Do

As a Senior Infrastructure Engineer, you’ll help design, build, and deliver secure digital solutions in highly secure environments. You’ll work alongside engineers, architects, and delivery specialists to develop technology that enables faster, safer decision‑making for critical operations.

Your work may include:

• Maintain, improve, and secure SiXworks’ multi‑classification, virtualised, collaboration and development environments.
• Work with IT infrastructure colleagues to improve SiXworks’ ‘Secure by Design’ capabilities, internally and across its projects.
• Provide Infrastructure support to SiXworks’ public cloud SaaS offerings (Office 365) as well as project‑based systems (public, private and hybrid clouds) in implementation and support lifecycles.
• Perform maintenance tasks on the infrastructure through change control.
• Assist with monitoring and management of SiXworks’ and project‑based ticketing and alerting systems for new changes and security alerts.
• Triage monitoring alerts and perform appropriate action.
• Maintain monitoring components in line with infrastructure developments.
• Ensure all platforms are patched in line with provider recommendations and SiXworks security policy.
• Quickly and accurately assess impact of incidents, initiate return to service and ensure follow‑up actions are completed.
• Identify trends and problems and plan changes to improve stability and performance.
• Maintain cutting edge knowledge and skills in the design and build of secure public, private, and hybrid cloud and network technologies.
• Develop personal knowledge through study/research toward vocational certifications in relevant technologies/vendors.
• Advise customers and project teams on infrastructure and support aspects.
• Cascade knowledge through knowledge articles for the team and wider organisation.
• Support the SiXworks team in winning business.

What We’re Looking For

We value people who take ownership, think critically, and enjoy working as part of a collaborative team tackling complex challenges. You don’t need to tick every box, but we’re particularly interested in people with skills/experience in:

• Team Player
• Windows Server 2016+ administration.
• RedHat Openshift
• EUD provisioning (Autopilot), maintenance, patching and hardening.
• SSO – concepts and operation.
• Understanding of working in protectively marked environments.
• VMware
• Networking
• Automation (scripting ansible/powershell)
• Kubernetes administration e.g. VMware TKGI
• VMware vSphere/vCenter/VCF.
• DevSecOps Tooling
• Elastic
• Nessus
• Application Packaging
• HashiCorp Terraform
• HashiCorp Vault
• Experience working in Agile sprints

Just as important are curiosity, strong problem‑solving ability, and the motivation to continuously improve how technology is designed and delivered.

A word on UK Security Clearance

Due to the secure nature of the position and working environment, you must have or be eligible to obtain Security Clearance. More details relating to UK Security Clearance can be found here: United Kingdom Security Vetting: clearance levels - GOV.UK (

We offer competitive salaries and a package that supports your wellbeing and development, including 25 days annual leave + bank holidays, free private medical cover and life assurance, generous pension (10% employer, 5% employee contribution), bonus and professional development and training support. In addition to secure parking, gym, café & restaurant on site and lots of open breakout spaces.

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