Senior Cyber Security Architect & Engineering Lead - Remote

REX Cyber Security; Greater London; Hybrid; GBP 110,000 - 140,000; Full time

Job summary

REX Cyber Security, a leading UK professional services firm, seeks a Cyber Security Architect & Engineering Lead to own security across Microsoft 365, Azure, Entra ID, Defender XDR, Sentinel, and Purview. This senior, hands-on role blends architecture and engineering to secure cloud, data, endpoints, apps and networks while enabling AI adoption.

You will lead security reviews, threat modelling and automation using Python, PowerShell, and Azure Functions; drive ISO 27001 and Cyber Essentials

Qualifications

• Hands-on experience in a Microsoft-centric security environment.
• Experience designing and implementing security controls across Microsoft 365, Azure and related tools.
• Ability to perform threat modelling and lead architecture reviews.

Responsibilities

• Design and implement security architecture across Microsoft 365, Azure, Entra ID, Defender XDR, Sentinel and Purview.
• Build modern security controls around Zero Trust, secure-by-design and automation.
• Lead architecture reviews and threat modelling for major projects and new technologies.
• Drive secure adoption of Microsoft 365 Copilot, AI agents and custom AI applications.
• Improve security monitoring, detection engineering and incident response.
• Support complex security incidents with internal teams and SOC partners.
• Strengthen vulnerability management using threat intelligence and risk.
• Automate security processes using Python, PowerShell, Logic Apps, Azure Functions and APIs.
• Provide evidence for ISO 27001 and Cyber Essentials Plus.

Skills

Threat modelling

Security architecture

Stakeholder communication

Security automation

Tools

Defender XDR

Sentinel

Entra ID

Azure

Microsoft 365

Purview

PowerShell

Python

Logic Apps

Azure Functions

APIs

Job description

REX Cyber Security, a leading UK professional services firm, seeks a Cyber Security Architect & Engineering Lead to own security across Microsoft 365, Azure, Entra ID, Defender XDR, Sentinel, and Purview. This senior, hands-on role blends architecture and engineering to secure cloud, data, endpoints, apps and networks while enabling AI adoption.

You will lead security reviews, threat modelling and automation using Python, PowerShell, and Azure Functions; drive ISO 27001 and Cyber Essentials