Principal Network Engineer

Job Description:

Are you ready to take on complex technical challenges and shape secure networks that underpin the UK’s most critical missions? At Leonardo, our Principal Network Engineers are recognised as subject matter experts, providing advanced technical authority and leading the design, integration, and delivery of resilient network solutions.

Your work at Leonardo UK will see you take the lead in solving customer problems in an agile, innovative and team-centric manner. The role may involve a blended hybrid working model, with a mixture of working from home and working on site at one of our Leonardo offices to ensure close collaboration with the wider team and with our customers.

• Act as the technical authority across one or more networking domains (LAN/WAN, cloud, security, or SDN).
• Lead the design and implementation of secure networks across on-premise, hybrid, and cloud environments.
• Capture and analyse complex requirements, shaping high- and low-level network designs.
• Ensure secure-by-design principles are embedded across all network solutions.
• Own technical delivery within work packages, including planning, estimation, and reporting.
• Provide guidance, mentoring, and technical leadership to junior and senior network engineers.
• Support technology assessments, innovation projects, and roadmap development.
• Engage with customers, stakeholders, and vendors to define and defend technical solutions.

• Extensive technical expertise across multiple networking domains with proven delivery experience.
• Ability to balance hands‑on engineering with technical leadership and solution ownership.
• A problem‑solving mindset with the ability to innovate and recommend the best approaches for complex challenges.

• Deep understanding of networking protocols and technologies (BGP, OSPF, MPLS, VPNs, QoS, IPsec, MCLAG).
• Experience with Cisco (CCNP level) or equivalent multi‑vendor technologies (Dell, Palo Alto, Fortinet).
• Strong knowledge of firewalls, IDS/IPS, and network security principles.
• Experience designing and integrating networks within secure environments.
• Experience with cloud networking (AWS, Azure) and hybrid integration.
• Familiarity with network automation and scripting (Python, Ansible, Terraform).

• Full CCNP or equivalent certification/experience (4-7 years).
• Experience with software‑defined networking (SDN, SD‑WAN) and cloud‑native networking.
• Knowledge of Dev Sec Ops  pipelines and integration with security monitoring tools (SIEM, SOC platforms).
• Involvement in industry forums, technical publications, or best‑practice development.
• Experience with enterprise IT services (Active Directory, DNS, PKI, monitoring).

This is not an exhaustive list, and we are keen to hear from you even if you might not have experience in all the above. The most important skill is a good attitude and willingness to learn.

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:

This role can be based at one of our UK sites Gloucester, with hybrid/custom working options where appropriate.

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,…