Senior IT Systems Administrator

Senior IT Systems Administrator / Bristol (3 days on-site) / £50,000–£60,000 | DV Clearance Eligibility Required

Take ownership. Solve complex challenges. Make IT better.

TwinStream is looking for an experienced Senior IT Systems Administrator to help keep our IT systems secure, resilient and performing at their best. This is a hands-on senior role offering the autonomy to tackle complex technical challenges, drive improvements, introduce automation and support colleagues across a growing business.

About TwinStream

Founded in 2019 by engineers solving complex challenges within government organisations,

TwinStream combines deep technical expertise with outstanding client service. We''ve since grown to more than 100 people across the UK, with colleagues working on-site, remotely and in hybrid environments.

The Senior IT Systems Administrator Role

You''ll take senior operational responsibility for TwinStream''s corporate IT estate, ensuring systems remain secure, reliable and fit for the future. Working alongside the IT Technical Lead, you''ll turn technical priorities into practical improvements while using your expertise to resolve issues, guide colleagues and enhance service delivery.

Your responsibilities will include:

• Managing the performance, resilience and lifecycle of cloud services, infrastructure, devices and applications.
• Administering Microsoft 365, Entra ID, identity and access management, endpoint security and corporate SaaS applications.
• Maintaining corporate networks, including firewalls, switches, wireless, VPN, DNS and DHCP.
• Implementing configuration changes, integrations and automation to improve efficiency and consistency.
• Monitoring service health, capacity, performance and security, proactively addressing risks and vulnerabilities.
• Leading complex incident resolution, root-cause analysis and security investigations.
• Coordinating patching, upgrades, backups, recovery testing and business continuity arrangements.
• Maintaining technical documentation, operational procedures, asset records and IT service-management standards.
• Mentoring colleagues, working with suppliers and stakeholders, and recommending improvements to support future priorities.

What We''re Looking For

You''ll bring proven experience in systems administration, infrastructure engineering or a similar technical role, alongside the confidence to work autonomously and take ownership of complex challenges.

Essential experience and skills:

• Strong Microsoft 365 administration and optimisation skills.
• Microsoft Entra ID, including SSO, Conditional Access, Identity Governance and Zero Trust principles.
• Corporate networking, including firewalls, switching, wireless, VPN, DNS and DHCP.
• Managing Windows, Linux and mobile devices, including endpoint management and secure configuration.
• PowerShell or similar scripting tools to automate tasks and improve efficiency.
• Cloud services, SaaS applications, collaboration tools and development-support services.
• IT security, vulnerability management, patching, monitoring, backups and disaster recovery.
• Incident management, root-cause analysis and security incident response, ideally involving SIEM tools.
• IT service management covering incidents, problems, changes and assets.
• Strong troubleshooting, risk assessment, prioritisation and communication skills.
• Experience guiding colleagues, maintaining technical documentation and working with suppliers.

Desirable: Intune, Landscape, JumpCloud, Atlassian or similar tools; ITIL Foundation; Infrastructure as Code; AWS or Azure; ISO 27001; Cyber Essentials Plus; UK public-sector experience; and involvement in agile delivery or developing IT policies and standards.

You don''t need to meet every requirement. If you have strong technical foundations and a proactive approach to improving IT services, we''d love to hear from you.

What''s in It for You?

• £50,000–£60,000 salary
• 28 days'' holiday plus bank holidays, with the option to buy or sell an additional week
• Annual bonus
• 8% non-contributory pension
• Private healthcare
• Critical illness cover
• Life insurance
• Enhanced parental leave
• Flexible working
• Learning, development and career progression opportunities
• A supportive and inclusive team environment
• The opportunity to work on meaningful projects

Ready for Your Next Challenge?

Join TwinStream and help deliver secure, reliable and continually improving IT services in a role where your expertise and initiative can make a real difference.

Apply today!