Senior IT Systems Administrator Location: Gloucestershire, UK (On-Site) Employment Type: Full-time, Mid-Senior level About the Opportunity Sanderson is collaborating with a leading global technology organisation that delivers mission-critical services in secure environments for government and national security clients. The team is expanding and seeking a skilled Senior IT Systems Administrator to join a high-performance environment supporting critical infrastructure operations. In this role, you’ll work across multiple teams to ensure stability, performance, and compliance across enterprise systems — maintaining secure IT environments and helping drive continual service improvement through innovation and best practice. Key Responsibilities Provide 1st and 2nd line technical support across complex IT environments Monitor system performance to ensure uptime, reliability, and efficiency Develop, maintain, and update system documentation Implement and enforce operational standards, policies, and procedures Support compliance initiatives and internal process improvements Essential Skills & Experience Strong background in Windows Server Administration (2016/2019) Experience working to ITIL best practices Excellent organisational and time management skills Analytical mindset with a proactive approach to identifying risks and improvements Strong communication and collaboration skills, with a willingness to share and learn Desirable Technologies & Experience Installation, upgrade, configuration, and support experience with Windows Server, AWS, and Azure Strong understanding of Active Directory (object creation, OU management, RBAC, DFS) Knowledge of virtualisation technologies : VMware, vSphere, vSAN, SCVMM, Hyper-V Familiarity with containerisation tools and technologies Networking fundamentals: TCP/IP, DHCP, DNS, LAN/WAN Scripting experience in PowerShell Awareness of McAfee EPO/ENS security tools Security Clearance Requirements Due to the nature of the work, candidates must be eligible for national security clearance. To meet this requirement, applicants must: Be sole British citizens (dual nationality is not permitted) Have not spent more than 30 consecutive days outside the UK in the past 10 years Have no criminal record Have no significant financial irregularities (e.g. bankruptcy, unpaid debt) Unfortunately, candidates who do not meet these criteria cannot be considered for this position. Why You’ll Enjoy Working Here Competitive salary and comprehensive benefits package Hybrid working model balancing flexibility and collaboration Career growth opportunities through continuous learning and development Work on high-impact, nationally significant projects Inclusive, people-first culture focused on wellbeing and professional excellence