Principal Platform Engineer

Job Description:

Salary Range: £60,000 - £71,400

Leonardo UK operates a grade-based salary framework with broad bands. The salary range shown reflects the approved grade band for this role, or a narrower hiring range published within that band, and is benchmarked against the external market. Exceptions above the standard range are managed through governance controls to protect internal equity.

Leonardo is looking for a 3rd Line Platform Engineer to join our collaborative and skilled team supporting a critical MOD site. This is an exciting opportunity to serve as a Subject Matter Expert (SME) in Windows-based enterprise infrastructures. You'll play a central role in the design, deployment, and support of high-security systems that underpin key defence and aerospace operations.

This role is based full-time on site in London and requires DV clearance.

• Take ownership of complex technical issues through to resolution, collaborating with users and other IT teams.
• Provide expert-level troubleshooting for incidents escalated from 1st and 2nd line support, ensuring consistent and minimal disruption to services.
• Deploy and integrate secure Windows Server environments (Active Directory, Group Policy, DNS, DHCP) using industry best practices.
• Implement and maintain infrastructure security measures such as patching, access controls, and hardening to align with compliance and internal governance.
• Use monitoring tools to proactively optimize system performance and ensure high availability.
• Create and maintain detailed technical documentation and contribute to internal knowledge sharing and mentoring.
• Participate in IT projects, ensuring infrastructure design meets both technical and business objectives.
• Collaborate closely with network, security, and application teams to deliver reliable, secure IT services.

• Proficiency in Ivanti Application & Device Control or similar lockdown tools.
• Experience working with high-security MOD systems and secure design principles.
• Familiarity with security and compliance documentation (e.g. RMADS, SyOPs, NIST frameworks).

Microsoft:

• Windows Server 2019/2022/2025
• Active Directory, Group Policy, DNS, DHCP
• Exchange Server 2019, SQL Server, SharePoint 2019

VMware:

• VMware Cloud Foundation
• vSphere, ESXi, NSXT, and vSAN

Endpoint & Configuration:

• Windows 10 & 11
• Microsoft Endpoint Configuration Manager (MECM)

Monitoring & Observability:

• Microsoft System Centre Operations Manager (SCOM)

PKI Technologies:

• Microsoft Certificate Services, Hardware Security Modules (HSMs), and lifecycle key management

This role is subject to pre-employment screening in line with the UK Government’s Baseline Personnel Security Standard (BPSS). An additional range of Personnel Security Controls referred to as National Security Vetting (NSV) may apply, this could include meeting the eligibility requirements for The Security Check (SC) or Developed Vetting (DV). For more information and guidance please visit

At Leonardo, our people are at the heart of everything we do. We offer a comprehensive, company-funded benefits package that supports your wellbeing, career development, and work-life balance. Whether you're looking to grow professionally, care for your health, or plan for the future, we’re here to help you thrive.

• Time to Recharge: Enjoy generous leave with the opportunity to accrue up to 12 additional flexi-days each year.
• Secure your Future: Benefit from our award-winning pension scheme with up to 15% employer contribution.
• Your Wellbeing Matters: Free access to mental health support, financial advice, and employee-led networks championing inclusion and diversity (Enable, Pride, Equalise, Armed Forces, Carers, Wellbeing and Ethnicity).
• Rewarding Performance
  :
  All employees at management level and below are eligible for our bonus scheme.
• Never Stop Learning
  :
  Free access to 4,000+ online courses via Coursera and Linked In Learning.
• Refer a friend: Receive a financial reward through our referral programme.
• Tailored Perks
  :
  Spend up to £500 annually on flexible benefits including private healthcare, dental, family…