IT Infrastructure Platform Architect

Colt Technology Services; Greater London; On-site; GBP 70,000 - 95,000; Full time

Job summary

Colt Technology Services Group Ltd. is seeking a Senior IT Infrastructure Engineer to lead the engineering, implementation, and operational support of Microsoft 365, Azure, Exchange Online and Identity platforms.

You will deliver secure, automated, and resilient cloud solutions, collaborate across Architecture, Security, Development and Operations, and participate in an on-call rota to ensure 24/7 platform reliability.

Qualifications

• Extensive experience in engineering and supporting Exchange Online, Identity, workplace, and Azure Cloud.
• Strong expertise across: Microsoft 365 configuration, administration, and security.
• Strong expertise in Exchange Online and Microsoft 365 administration.
• Experience with Defender for Office 365 and Exchange Online Protection.
• Understanding of email authentication technologies including SPF, DKIM, and DMARC.
• Experience with Purview, Compliance Center, and retention policies.
• Manage mail flow, connectors, transport rules, accepted domains, and email security policies.
• Perform tenant-level Exchange administration using EAC and PowerShell.
• Identity and access (Active Directory, Entra ID, authentication, access control)
• Support identity integration with Entra ID (Azure AD), AD, and AAD Connect.
• Security configuration and resilience practices
• Automation and operational tooling (PowerShell, scripts, IaC concepts)
• Strong troubleshooting and problem-solving capability
• Experience working in enterprise-scale environments.

Responsibilities

• Implement and operate infrastructure and platform solutions aligned to architectures, standards, and patterns.
• Build, configure, and operate end-to-end cloud, M365, and identity solutions.
• Act as senior escalation points for engineering and operational issues.
• Implement and operate secure-by-design configurations.
• Ensure resilience, recoverability, monitoring, and operational readiness are delivered and sustained.
• Deliver and operate roadmap initiatives and platform improvements.
• Support planning and execution of engineering and operational changes.
• Work with Architecture, Security, Development, and Infrastructure teams to deliver integrated solutions.
• Ensure solutions are tested, transitioned, and fully operational.
• Work with vendors to support implementation, operation, and issue resolution.
• Contribute to platform, tooling, and operational improvements.
• Ensure solutions align to standards and are maintained through BAU lifecycle.
• Support incident, problem, and continuous service improvement activities.
• Implement and operate automation-first solutions.
• Reduce manual effort, technical debt, and complexity.
• Improve stability, consistency, and operational efficiency at scale.
• Participate in an on-call rota for priority incident support.
• Ownership & Execution: Delivers reliable, secure solutions end-to-end, translating design into high-quality implementation.
• Technical Leadership: Acts as SME across cloud, M365, and identity, resolving complex technical challenges.
• Collaboration & Influence: Works effectively across teams, contributing to design decisions and stakeholder outcomes.
• Adaptability & Improvement: Responds to challenges while driving automation, optimisation, and clear communication.

Skills

Exchange Online

Azure Cloud

Microsoft 365

Identity & Entra ID

Automation tooling

PowerShell

Security & Compliance

On-call support

Enterprise IT

Threat protection

Tools

Exchange Admin Center (EAC)

PowerShell

IaC concepts

Microsoft Purview

Defender for Office 365

Job description

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The Senior IT Infrastructure Engineer (M365, Azure, Exchange online & Identity) is responsible for the engineering, implementation, and operational supportof Microsoft 365, Azure, Exchange online and enterprise identity (AD/Entra).

The role delivers secure, standardised, and automated solutions, translating architectural designs, standards, and roadmaps into robust, scalable platform implementations and operational services.

Working as a senior technical expert within the engineering team, the role collaborates with Architecture, Security, Development, and Operations teams to ensure solutions are delivered, integrated, and operated effectively.

It embeds security, resilience, automation, and operability by implementation, driving consistency and optimisation across M365, Azure, Exchange online, and Identity platforms. Through engineering excellence, the role reduces risk, complexity, and manual effort, improves resilience and service stability, and supports cost-efficient platform operations.

What you will do

Engineers and supports solutions across M365, Azure, Exchange online and Identity, ensuring platforms, tooling, interfaces, and configurations are secure, resilient, automated, and operationally effective.

• Microsoft 365 Platforms: Implementation, configuration, and support of collaboration and productivity services (inc. Teams, Exchange, SharePoint, OneDrive, Intune), including governance controls, security settings, and lifecycle activities
• Azure Cloud: Deployment and support of landing zones, subscriptions, connectivity, platform services, and governance controls aligned to architectural standards
• Exchange Administration: Design, implement, administer, and support Microsoft Exchange Online within a Microsoft 365 environment.
• Identity & Access: Engineering and operation of Active Directory and Entra ID, including authentication, Conditional Access, privileged access, identity governance, and directory integration
• Cloud Security & Compliance: Implementation and maintenance of secure configurations, monitoring, logging, encryption, and policy enforcement across cloud and identity platforms
• Delivers and supports standardisation, automation, tooling, and consistency across cloud, workplace, and identity platforms

Key Accountabilities

1. Solution Engineering & Operation
Implement and operate infrastructure and platform solutions aligned to architectures, standards, and patterns
Build, configure, and operate end-to-end cloud, M365, and identity solutions
Act as senior escalation points for engineering and operational issues

2. Security, Resilience & Operability
Implement and operate secure-by-design configurations
Ensure resilience, recoverability, monitoring, and operational readiness are delivered and sustained

3. Roadmap Execution
Deliver and operate roadmap initiatives and platform improvements
Support planning and execution of engineering and operational changes

4. Cross-Domain Collaboration
Work with Architecture, Security, Development, and Infrastructure teams to deliver integrated solutions
Ensure solutions are tested, transitioned, and fully operational

5. Vendor & Technology Engagement
Work with vendors to support implementation, operation, and issue resolution
Contribute to platform, tooling, and operational improvements

6. Operational Governance & Support
Ensure solutions align to standards and are maintained through BAU lifecycle
Support incident, problem, and continuous service improvement activities

7. Automation, Standardisation & Optimisation
Implement and operate automation-first solutions
Reduce manual effort, technical debt, and complexity
Improve stability, consistency, and operational efficiency at scale

Operational Support
Participate in an on-call rota for priority incident support

Leadership & Behavioural Expectations

• Ownership & Execution: Delivers reliable, secure solutions end-to-end, translating design into high-quality implementation
• Technical Leadership: Acts as SME across cloud, M365, and identity, resolving complex technical challenges
• Collaboration & Influence: Works effectively across teams, contributing to design decisions and stakeholder outcomes
• Adaptability & Improvement: Responds to challenges while driving automation, optimisation, and clear communication

What we're looking for

Skills & Experience

• Extensive experience in engineering and supporting Exchange online, Identity, workplace, and Azure Cloud
• Strong expertise across:
• Microsoft 365 configuration, administration, and security.
• Strong expertise in Exchange Online and Microsoft 365 administration.
• Experience with Microsoft Defender for Office 365 and Exchange Online Protection.
• Understanding of email authentication technologies including SPF, DKIM, and DMARC.
• Experience with Microsoft Purview, Compliance Center, and retention policies.
• Manage mail flow, connectors, transport rules, accepted domains, and email security policies.
• Perform tenant-level Exchange administration using Exchange Admin Center (EAC) and PowerShell.
• Identity and access (Active Directory, Entra ID, authentication, access control)
• Support identity integration with Microsoft Entra ID (Azure AD), Active Directory, and Azure AD Connect.
• Security configuration and resilience practices
• Automation and operational tooling (PowerShell, scripts, IaC concepts)
• Strong troubleshooting and problem-solving capability
• Experience working in enterprise-scale environments

Summary

A senior IT engineering role responsible for implementing and operating secure, automated, resilient, and scalable M365, Azure, GCP, and Identity platforms, ensuring solutions are delivered effectively and operated reliably while driving continuous improvement and operational excellence.