Principal P&C Platform Architect - M365

This job is with GSK, an inclusive employer and a member of my Gwork – the largest global platform for the LGBTQ+ business community. Please do not contact the recruiter directly.

At GSK, we unite science, technology and talent to get ahead of disease together. We are a global biopharma company with a special purpose – to unite science, technology and talent to get ahead of disease together. We’re proud to be leading a healthcare revolution, and we’re looking for people who can help us deliver on our ambition.

Role Overview

Own the architecture of the platform where 50,000+ employees across multiple countries actually do their work — email, files, meetings, chat, intranet, workflow and, increasingly, AI assistance. This role is the definitive technical authority for the Microsoft 365 estate:
Exchange Online, SharePoint Online, One Drive, Teams, Viva, Power Platform, Microsoft 365 Copilot, and the Entra  Purview controls that govern them.

Microsoft 365 is no longer a set of applications; it is a tenant-wide platform where an identity decision, a sharing default or a licensing choice propagates instantly to every user and every document. The Principal Platform Architect is accountable for making those decisions deliberately and coherently — balancing collaboration velocity against information protection, and platform capability against cost.

This is a hands‑on‑capable role. The expectation is to build, prove and pressure‑test designs in a lab tenant personally, and to be the person who understands what a setting actually does rather than what the documentation claims.

In this role you will

• Own the target‑state architecture for the M365 tenant: workload topology, tenant and domain strategy, identity and licensing model, data residency, and the integration surface with the wider application estate.
• Define the multi‑year productivity and collaboration roadmap — workload adoption and retirement, migration off legacy platforms (on‑premises Exchange/SharePoint, file shares, third‑party collaboration tools), and consolidation of overlapping tooling.
• Track the Microsoft 365 roadmap and message centre continuously; assess incoming change for risk and opportunity, and decide what the organisation adopts, defers, or disables — before Microsoft decides for you.
• Produce and maintain reference architectures, design patterns and architecture decision records (ADRs) with trade‑offs made explicit.
• Architect information protection across the tenant:
  Microsoft Purview sensitivity labels, retention and records management, DLP, eDiscovery, insider risk, and Communication Compliance.
• Design the external sharing, guest access and B2B collaboration model — the single most consequential and most frequently mis‑set area of the platform.
• Ensure the tenant meets regulatory obligations: data privacy (GDPR and equivalents), data residency and Multi‑Geo, GxP and validated‑system requirements, records retention, legal hold, and audit/SOX ITGC evidence generation designed in rather than bolted on.
• Partner with Cyber Security on tenant security posture — Conditional Access, Defender for Office 365, Defender for Cloud Apps, Secure Score, token and session controls, and the endpoint's role in tenant trust.
• Own the architecture for Microsoft 365 Copilot and agent platforms: readiness assessment, permission and oversharing remediation, semantic index behaviour, grounding and data boundaries, licensing strategy and measurable value realisation.
• Establish governance for Copilot Studio and agent creation — who may build, on what data, with what review and lifecycle.
• Set the position on AI data handling and prompt/response retention that Legal, Privacy and the Works Council will accept.
• Architect the Power Platform environment strategy:…