Systems Administrator - Platform Migration & Merge Specialist

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 June
26-Mar
27)

Reporting To: The IT Director

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, cut‑over and stabilisation activities that surround them.

• 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 One Drive 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 cut‑over activities including domain MX changes, primary SMTP swaps, UPN transitions, and the controlled retirement of source environments.
• Write and maintain Power Shell scripts that interact with Exchange Online, Microsoft Graph, Entra  SharePoint for bulk operations, validation, reporting and automation.

• 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, Power Shell, 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 IMPORT RANGE.
• Document findings and recommend approaches to address them.

• Plan and implement identity strategies that accommodate Entra , 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.

• 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 e sign‑on.

• 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.

• Provide hyper‑care support during and after migration cut‑overs.
• 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.

• Strong…