Security Administrator in Gloucester

Defender Administrator

Location: Gloucester or Warrington, UK (Hybrid with shift and on-call work as required)
Type: Contract (6 months+) | Rate: Market (Inside IR35)
Start Date: 15 September 2025
Clearance: Must hold or be eligible for UK Security Clearance (5 years minimum UK residency)

About the Role

Our client, a leading global organisation, is seeking a Defender Administrator to play a key role in the migration of Windows 10 endpoints from legacy antivirus platforms (Symantec, McAfee) to Microsoft Defender for Endpoint (ATP). You will oversee onboarding, configuration, and policy deployment across enterprise environments, ensuring robust endpoint security in line with best practices.

This is a hands-on role requiring strong technical expertise in Microsoft Defender and Windows environments, with responsibilities spanning migration, monitoring, troubleshooting, and continuous security improvement.

Key Responsibilities:

• Lead the migration of Windows 10 endpoints from Symantec/McAfee to Microsoft Defender for Endpoint (ATP).
• Onboard devices to Microsoft Defender and remove legacy AV solutions.
• Configure and manage Defender policies, exclusions, dashboards, and reporting.
• Deploy Defender ATP packages via GPO, SCCM, or Intune.
• Ensure best-practice endpoint security controls, including EDR, TVM, ASR, and AIR.
• Conduct threat analysis, hunting, and remediation activities across endpoints.
• Support and troubleshoot escalated issues across Windows clients and servers.
• Collaborate with EUC, infrastructure, and application teams to ensure smooth rollout.
• Maintain up-to-date documentation on configurations, policies, and procedures.
• Provide out-of-hours/on-call support on a rota basis when required.

Required Skills & Experience:

• 4+ years experience in endpoint security administration, with hands-on Microsoft Defender expertise.
• Strong knowledge of Microsoft Defender for Endpoint, O365, Identity, 365 Defender, and Cloud App Security.
• Experience migrating from Symantec Endpoint Protection (SEPM) and/or McAfee.
• In-depth knowledge of Windows client and server operating systems (Win 7/8/10, Server 2008/2012/2016).
• Proficiency with GPO, SCCM, Intune for endpoint deployment and management.
• Investigative and analytical problem-solving skills across Windows infrastructure.
• Experience with endpoint detection, threat hunting, and vulnerability remediation.
• Strong documentation, process, and reporting skills.
• Excellent communication and stakeholder engagement abilities.

Desirable:

• Industry certifications in Microsoft Security (e.g., SC-200, SC-300) or related areas.
• Previous experience in large-scale migration projects.
• Familiarity with enterprise compliance and governance frameworks.

• Contribute to a high-profile enterprise security transformation.
• Be part of a collaborative and technically skilled team delivering critical endpoint protection.
• Gain exposure to the latest Microsoft security technologies across large environments.
• Opportunity to shape security best practices in a high-security, compliance-driven environment.