Systems Administrator

Systems Administrator - Platform Migration & Merge Specialist

Location: Basingstoke (hybrid)

Job Type: Fixed Term Contract (Until 31st March 2027)

Salary: £50k - 80k (Pro Rated for period of hire June26-Mar27)

Reporting To: The IT Director

Key Responsibilities:

Google Workspace to M365 and M365 to M365 Migrations

Role Overview

Reporting to the IT Director, this role provides the technical leadership and hands-on delivery required to continue a multi-phase collaboration platform consolidation programme across the group. The programme is migrating several business units onto a single Microsoft 365 tenant, retiring legacy Google Workspace and standalone Microsoft 365 environments along the way.

You will be responsible for overseeing in-flight migrations, planning and executing future migrations, and decommissioning environments that have already been transitioned. The work spans Microsoft 365 tenant-to-tenant migrations, Google Workspace to Microsoft 365 migrations, and the coexistence, cutover and stabilisation activities that surround them.

Key Responsibilities

Migration Delivery

• Take ownership of in-flight and upcoming platform migrations, including both Microsoft 365 to Microsoft 365 (tenant consolidation) and Google Workspace Enterprise to Microsoft 365 transitions.

• Design and execute migration approaches for mail, calendars, contacts, files, chat and identity, using the Microsoft Migration Toolset (Exchange Online migration, SharePoint and OneDrive migration tooling) and complementary third-party tooling where appropriate.

• Manage coexistence periods where dual systems operate in parallel, including mail flow configuration, calendar interop, free/busy visibility, and delta synchronisation.

• Plan and execute cutover activities including domain MX changes, primary SMTP swaps, UPN transitions, and the controlled retirement of source environments.

• Write and maintain PowerShell scripts that interact with Exchange Online, Microsoft Graph, Entra ID and SharePoint for bulk operations, validation, reporting and automation.

Discovery and Analysis

• Develop a thorough understanding of source environments before migration, including users, groups, mail, files, shared drives, calendar resources, chat, third-party integrations and operational workflows.

• Use Google Admin tools, GAM, Microsoft Graph, PowerShell, Microsoft Migration Manager and other appropriate tooling to query, analyse and report on source data.

• Identify migration risks, edge cases and dependencies, including shared mailboxes, delegations, calendar resource booking, SaaS authentication dependencies, and cross-document references such as Google Sheets IMPORTRANGE.

• Document findings and recommend approaches to address them.

Identity, Licensing and Coexistence

• Plan and implement identity strategies that accommodate Entra ID, Google federation and the broader SaaS application landscape during transitions.

• Manage licensing transitions across Microsoft 365 and Google Workspace, including Cloud Identity downgrades for retained identity-only accounts.

• Maintain mail flow integrity across domains during coexistence, including accepted domain types, forwarding configurations, primary SMTP and alias management.

Tenant Decommissioning

• Oversee the controlled decommissioning of source environments after successful migration, covering data retention, identity downgrade, licence release and tenant retirement.

• Coordinate retention of legacy native content as a safety net where required.

• Manage SaaS application transitions from legacy identity providers to Entra ID single sign-on.

Stakeholder Engagement and Proposal Support

• Provide the technical analysis and detailed planning required by the IT Director and CTO to build migration proposals for leadership approval.

• Communicate progress, risks and decisions through Steering Committee forums.

• Translate technical detail for non-technical audiences in user communications, change management materials and service desk guidance.

Post-Migration Support

• Provide hypercare support during and after migration cutovers.

• Engage directly with senior stakeholders and VIP users to triage and resolve complex issues.

• Iterate on the support model based on real-world feedback and post-migration metrics.

What We're Looking For

Essential

• Strong administrative expertise in Microsoft Entra ID, Microsoft 365 (Exchange Online, SharePoint Online, OneDrive, Teams) and Google Workspace Enterprise.

• Proven experience delivering tenant-to-tenant Microsoft 365 migrations and Google Workspace to Microsoft 365 migrations.

• Strong PowerShell skills, including writing scripts that interact with Microsoft Graph, Exchange Online and Entra ID for import, export, validation and automation tasks.

• Hands-on experience with the Microsoft Migration Toolset (Exchange Online migration, SharePoint Migration Manager, OneDrive migration) and Google Workspace admi