Senior Systems Administrator: Lead IT Ops & Security

Shield; Greater London; On-site; GBP 55,000 - 75,000; Full time

Job summary

Shield AI is seeking a Systems Administrator to support, secure, and optimize enterprise IT operations across Windows and Linux environments. You will work with infrastructure, network, and security teams to maintain a scalable and secure IT environment.

This role includes on-call rotations, asset lifecycle management, and mentoring junior staff, with opportunities to shape IT practices and documentation. A strong foundation in AD/Azure AD, scripting, and ITIL is valued.

Qualifications

• 3+ years of experience in systems administration or enterprise desktop support roles.
• Strong proficiency in Windows and Linux operating systems.
• Experience with Active Directory, Azure AD, and identity/access management tools.
• Knowledge of networking fundamentals (TCP/IP, DNS, DHCP) and endpoint security practices.
• Familiarity with IT asset management platforms (e.g., SNIPE, JSM, JIRA).
• Ability to participate in an on-call rotation and off-hours maintenance windows.
• Strong documentation, troubleshooting, and customer service skills.
• Excellent communication and collaboration across technical and non-technical teams.

Responsibilities

• Provide hands-on desktop, server, and systems administration support for Windows and Linux environments.
• Install, configure, and troubleshoot hardware and software issues across end-user devices and server systems.
• Administer user accounts, access control, and group policies using Active Directory and Azure AD.
• Manage IT assets throughout their lifecycle: procurement, deployment, support, and decommissioning.
• Ensure proper inventory control, software licensing compliance, and asset tracking using IT asset management tools.
• Generate reports on hardware/software usage, compliance, and asset depreciation for internal and audit needs.
• Lead and mentor junior administrators and support staff; contribute to technical documentation and team training.
• Participate in on-call rotation and perform maintenance activities outside business hours as required.
• Collaborate with infrastructure, network, and security teams to support enterprise IT operations and incident response.

Skills

Windows/Linux

AD/Azure AD

Networking basics

Asset management

Documentation

On-call

Team collaboration

Tools

SNIPE

JSM

JIRA

Intune

PowerShell

Job description

Shield AI is seeking a Systems Administrator to support, secure, and optimize enterprise IT operations across Windows and Linux environments. You will work with infrastructure, network, and security teams to maintain a scalable and secure IT environment.

This role includes on-call rotations, asset lifecycle management, and mentoring junior staff, with opportunities to shape IT practices and documentation. A strong foundation in AD/Azure AD, scripting, and ITIL is valued.