Senior IT Systems Administrator

📋 Job Overview

In 2019, the founders were working as engineers solving complex cross-domain problems within government organisations. TwinStream was formed to bring together their collective expertise and experience into a single business, focused on delivering technical excellence and high-quality service to clients. Since then, the company has grown to over 100 team members across the UK, with colleagues working both on-site with clients, hybrid and remotely from home.

🏢 About TwinStream

TwinStream was formed to bring together their collective expertise and experience into a single business, focused on delivering technical excellence and high-quality service to clients.

🎯 The Role

As a Senior IT Systems Administrator, you’ll take senior operational responsibility for the performance, resilience, maintenance and continual improvement of TwinStream’s IT systems and services, helping ensure they remain secure, reliable and fit for purpose as the business grows. Working within the strategy, architecture, standards and technical priorities set by the IT Technical Lead, you’ll translate agreed priorities into well-planned and sustainable improvements across the corporate IT estate. This is a hands-on senior role requiring sound technical judgment, leadership of complex technical implementation, resolution of high-impact issues and guidance for colleagues across the IT team.

✅ Key Responsibilities

• Leading the day-to-day management of the operational performance, resilience and lifecycle of cloud services, corporate infrastructure, end-user devices and applications.
• Implementing, maintaining and recommending improvements to operational standards for identity and access management, Joiner, Mover and Leaver processes, endpoint management and asset management.
• Leading the technical implementation of configuration changes, automation and system integrations in accordance with agreed architecture, standards and change priorities.
• Administering and optimising cloud platforms, corporate SaaS applications, collaboration tools and development-support services, escalating material architecture, supplier or licensing decisions where required.
• Providing senior administration and operational assurance of the corporate network, including routers, switches, wireless services and associated network components.
• Monitoring service health, capacity, performance and security, identifying trends and taking proactive action to address risks before they affect users.
• Acting as the senior operational escalation point for complex incidents and problems, coordinating resolution, root-cause analysis and preventative action, and escalating critical or systemic issues to the IT Technical Lead.
• Planning and coordinating patching, vulnerability remediation and upgrades, balancing operational risk and business priorities within agreed technical and security requirements.
• Implementing, maintaining and testing backup, recovery and continuity arrangements in support of the disaster recovery approach defined by the IT Technical Lead.
• Maintaining the quality of technical documentation, operational procedures, asset information and system records, ensuring they remain accurate and usable.
• Mentoring colleagues, reviewing implementation approaches for alignment with agreed standards and promoting consistent, high-quality delivery.
• Identifying and analysing operational and technical improvements, distinguishing between service requests, small works and larger changes, and producing options, effort estimates and recommendations for prioritisation.
• Building effective relationships with stakeholders, technical partners and suppliers to coordinate technical delivery and resolve operational issues.

📌 Required Qualifications

• Proven experience in systems administration, infrastructure engineering or a comparable hands-on technical role, with responsibility for complex services or technical delivery
• A strong track record of managing business-critical IT services, making sound technical recommendations, resolving complex issues and delivering continual improvement, including assessing demand, distinguishing between service requests, small works and larger projects, and undertaking analysis and estimation to support prioritisation
• Strong practical knowledge of Microsoft 365 administration, optimisation and adoption, with the ability to recommend and implement improvements
• Strong practical knowledge of identity and access management using Microsoft Entra ID, including SSO, Conditional Access and Identity Governance, with experience applying Zero Trust principles such as least privilege, explicit verification and continuous risk assessment
• Practical experience managing corporate networks, including firewalls, switching, wireless, VPN, DNS and DHCP, with strong network troubleshooting skills
• Experience using PowerShell or comparable scripting tools to automate administration, improve consistency and reduce manual effort
• Strong analytical and troubleshooting skills, with the ability to assess risk and communicate technical options and recommendations clearly to technical and non-technical stakeholders
• Able to work autonomously, prioritise competing demands, exercise sound judgment, mentor colleagues and provide technical guidance
• Experience managing end-user devices across Windows, Linux and mobile platforms, including endpoint management, secure configuration, vulnerability remediation and information-protection controls
• Experience administering and optimising corporate SaaS applications and collaboration or development-support tools
• Experience monitoring service health, capacity, performance and security, and planning or assuring patching, backup, recovery and continuity arrangements
• Experience supporting security monitoring and incident response, including the use of SIEM tooling, escalation, root-cause analysis and preventative action
• A practical understanding of IT service management, including incident, problem, change and asset management
• Experience creating and maintaining clear technical documentation, operational procedures, asset information and system records
• Experience working effectively with technology suppliers and considering licensing, support and service-management requirements

⭐ Desirable Experience

• Hands-on experience with Intune, Landscape, JumpCloud, Atlassian products or comparable administration tools
• ITIL Foundation or an equivalent Service Management certification
• Experience with automation and Infrastructure as Code
• Experience of cloud infrastructure such as AWS and Azure.
• Experience working within ISO/IEC 27001, Cyber Essentials Plus or UK public-sector environments
• Experience contributing to agile delivery and developing IT policies, standards and procedures

🎁 Benefits

• Competitive salary and benefits package
• 28 days’ holiday plus bank holidays, with the option to buy or sell an additional week
• Annual bonus
• Critical illness cover
• 8% non-contributory pension
• Private healthcare and life insurance
• Enhanced parental leave
• Flexible working
• Opportunities for learning, development, and career progression
• Internal training and development
• The chance to work on meaningful projects

🛂 Visa & Eligibility

Due to the nature of the role and the work we do, any offer of employment will be subject to the successful completion of the security screening and vetting process. This role requires eligibility for UK Government's SC / DV clearance. As part of the vetting process, candidates must meet the UK Government's residency and right-to-work requirements at the required level of security clearance.