Senior Security Architect
First seen by Alion on Oct 23, 2026.
Role Overview:
As Senior Security Architect, you will be the senior technical adviser within the offshore consultancy team. Working under the technical direction of the UK Head of Service, you will produce the security architecture, design and risk material that underpins the service, and provide technical leadership to the offshore engineers. This is a design, review and advisory role.
Responsibilities:
- Produce and maintain security architecture and design documentation (high-level and low-level designs) for the client's security tooling estate.
- Carry out architecture and risk reviews of proposed high-risk changes (firewall, intrusion prevention, gateway, privileged access and application control).
- Define logging and audit requirements for in-scope security tools, including log sources and retention architecture.
- Assess and recommend tooling and approaches for PKI and secrets management.
- Produce NIS Regulations and NCSC Cyber Assessment Framework (CAF) alignment assessments.
- Prepare inputs for the client's governance, risk, and compliance (GRC) reporting.
- Develop risk treatment plans and maintain inputs to the security risk register.
- Prepare technical content and risk papers for the client's cyber security governance board.
- Maintain the master set of security architecture diagrams.
- Identify and assess continual improvement opportunities.
- Apply appropriate consideration of operational technology (OT) and IT/OT boundary risk.
- Provide technical leadership, peer review and mentoring to the engineering team.
- Support the growth of Expleo's Cybersecurity Practice.
Qualifications :
- Degree in computer science, cybersecurity, information systems or a related discipline, or equivalent professional experience.
- CISSP, CISSP-ISSAP or SABSA Chartered Foundation (at least one required).
- TOGAF, a cloud security certification (e.g. CCSP, AZ-500, AWS Security Specialty) or GICSP/ISA/IEC 62443 certification would be advantageous.
Essential Skills :
- Enterprise security architecture across network, identity, endpoint, cloud and data security domains.
- Designing logging and SIEM integration architectures.
- Applying risk assessment methods such as ISO/IEC 27005 and NIST SP 800-30.
- Working knowledge of the NIS Regulations, NCSC CAF, ISO/IEC 27001, NIST CSF and CIS Controls.
- Reviewing proposed changes for architectural and security risk.
- Excellent written communication for executive, governance and regulator-facing documentation.
- Ability to lead and quality-assure the work of other engineers.
Desired Skills:
- Energy, utilities or other CNI sector experience.
- Knowledge of OT/ICS security concepts, the Purdue model and IEC 62443.
- Experience with GRC tooling (e.g. ServiceNow IRM, Archer).
- Experience with Ofgem or NIS-regulated cyber assurance activity.
Experience:
- 12+ years in IT and cybersecurity, including 6+ years in security architecture for enterprise or CNI environments.
- Experience producing architecture, design and risk artefacts for regulated organisations.
- Experience supporting governance boards, risk registers and GRC reporting.
- Experience working with multi-supplier environments and managed security service providers.
Skills
Security Architect, CISSP, Information Security, Cyber Security, SIEM, IT Security Strategy, IT Audit, TOGAF, CISP, ISO, Security Tools