Senior Principal - P&C Platform Engineer

Business Introduction GSK remains committed to achieving bold commercial ambitions for the future. By 2031, we aim to deliver £40 billion in annual sales, leveraging our existing strong performance momentum to significantly increase our positive impact on the health of billions of patients globally. Our Ahead Together strategy is centred on early intervention to prevent and alter the course of disease, thereby protecting people and supporting healthcare systems. Our diverse portfolio consists of vaccines, specialty medicines, and general medicines. Through continuous innovation and a dedicated focus on scientific and technical excellence, we strive to develop and launch new, groundbreaking treatments that address critical health challenges. Job Purpose  Build, automate and run the platform that 50,000+ employees across [X] countries use to communicate and collaborate — Microsoft Teams, SharePoint Online and OneDrive, Exchange Online, the Microsoft 365 apps, Power Platform and Microsoft 365 Copilot. This is the hands-on build role. The Platform Engineer takes architecture direction and a prioritised backlog and turns them into working, tested, automated, documented configuration in production. The expectation is engineering rather than administration: configuration expressed as code and deployed through pipelines, not clicked through a portal and remembered by whoever was on shift. The role also runs what it builds. Platform Engineers own the operational health of their workloads — diagnosing the awkward, intermittent, only-happens-in-Tokyo problems that never reproduce in a lab, and eliminating the root cause rather than closing the ticket. Key Responsibilities • • Design, build, test and deploy configuration across the Microsoft 365 estate: Teams policies, SharePoint and OneDrive settings, Exchange Online transport and mail flow, Purview policies, Entra ID groups and Conditional Access as it applies to collaboration workloads. • Implement to the reference architecture and standards set by the Principal Architect; raise a design challenge when reality does not match the design rather than quietly deviating. • Deliver backlog items from sprint to production with the tests, telemetry, documentation and rollback path included — "done" means running and observable, not merely configured. • Build and maintain integrations using Microsoft Graph and platform APIs; write the connective tissue between M365, ServiceNow, HR systems and the wider application estate. • Automate everything that would otherwise be done twice. Provisioning, lifecycle, reporting, remediation, joiner/mover/leaver flows, licence assignment and reclamation. • Express tenant configuration as code in version control; build and maintain CI/CD pipelines for policy and solution deployment with automated validation and staged ring-based rollout. • Replace manual runbook steps with self-healing and self-service; treat a recurring manual task as a defect with a backlog item attached. • Own operational health of assigned workloads: monitoring, alerting, capacity, service health response and performance. • Investigate and resolve complex incidents and problems — third-line escalation for collaboration platform issues — and drive permanent root-cause elimination. • Participate in an on-call rotation for major incidents affecting the collaboration platform. • Manage the continuous change stream from Microsoft: assess message centre and roadmap items, test in a lab tenant, and implement, defer or disable with the reasoning recorded. • Maintain patch, currency and configuration compliance; remediate vulnerabilities and drift. • Implement and maintain security and information governance controls in the collaboration estate: sensitivity labels, DLP, retention, extern