Network Engineer

We are looking for an experienced Network Engineer to support and evolve secure, business-critical network services within UK government and defence environments. This is a service-based role, working across 1st to 4th line support teams, with the opportunity to contribute to project and change activities alongside live service operations. The role offers a hybrid working model, combining remote working with on-site presence at secure customer locations where required. What will I be doing?

• Lead network management and service acceptance activities, setting technical standards and providing subject-matter expertise to programme and delivery teams.
• Design, validate, and assure network solutions using formal verification and validation principles in secure environments.
• Produce and maintain high-quality technical documentation, including HLDs, LLDs, work instructions, and operational procedures.
• Support the operation and continuous improvement of live network services, ensuring availability, resilience, and compliance.
• Take ownership of complex incidents, driving investigation and resolution through to successful closure.
• Communicate effectively across technical, organisational, and customer boundaries, including within regulated and security-constrained environments.
• Participate in an on-call support rota following an initial onboarding and handover period.

• Strong, demonstrable experience with data centre and campus networking technologies, including:

• Cisco (routers, switches, firewalls)

• Fortinet firewalls

• Palo Alto firewalls

• Juniper (routers, switches, firewalls)

• F5 / Citrix

• In-depth understanding of network protocols, including:

• Routing: OSPF, BGP, EIGRP, Static

• Switching: VLAN / 802.1Q, (R/M)STP, Port Security, Layer 3 switching, LACP / EtherChannel

• VPLS, VPN, PKI, and load balancing

• Experience implementing and supporting AAA services, including TACACS+, within secure or regulated environments.

• Proven experience operating high-availability data centre networks.

• Hands-on experience with monitoring and management tooling such as SolarWinds, PRTG, and Panorama.

• Good working knowledge of Windows Server environments, including Active Directory, DNS, and DHCP.

Desirable Skills and Experience

• Experience working with AWS networking services in secure or regulated environments, including hybrid on-prem to cloud connectivity.
• Exposure to cloud-integrated or hybrid network architectures.

Required Personal Skills

• Excellent documentation skills, with the ability to produce clear, accurate, and auditable technical artefacts suitable for secure environments.
• Self-starter mentality, able to work independently, take ownership of tasks, and proactively identify and resolve issues.
• Strong analytical and problem-solving capability, with the ability to manage complex technical issues in secure environments.
• Excellent written and verbal communication skills.
• High levels of organisation, ownership, and attention to detail.
• Ability to work confidently in customer-facing roles and within security-restricted sites.

Security Clearance Requirements

• This role requires UK Security Check (SC) clearance or the ability to obtain it.
• Candidates must be UK nationals and have appropriate UK residency history to meet security vetting requirements.
• The role involves working on secure customer sites, where on-site attendance is mandatory.

At Leidos we are PASSIONATE about customer success, UNITED as a team and INSPIRED to make a difference. We offer meaningful and engaging careers, a collaborative culture, and support for your career goals, all while nurturing a healthy work-life balance. We provide an employment package that attracts, develops and retains only the best in talent. Our reward scheme includes:

• Contributory Pension Scheme

• Private Medical Insurance

• 33 days Annual Leave (including public and privilege holidays)

• Access to Flexible benefits (including life assurance, health schemes, gym memberships, annual buy and sell holidays and a cycle to work scheme)

• Flexi-Time Working

we work to make the world safer, healthier, and more efficient through technology, engineering and science. Leidos is a growing company delivering innovative technology and solutions focused on safeguarding critical capabilities and transformation in frontline services, our work in the United Kingdom includes addressing some of the most complex problems in defence, healthcare, government, safety and security, and transportation. What Makes Us Different: Purpose: you can use your passion and abilities at Leidos to keep the people you care about safe. We are at the forefront of machine learning, AI, cyber security and solutions. Using your skills in the technology frontline by helping to build a safer world. You can inspire change. Collaboration: having flexibility to do your job is one of our core benefits, enabling you to become part of our extraordinary team. We have been empowering our people to work flexibly for years. Whether you work from home, the office or on customer sites, we will give you the digital tools and the flexibility to work smarter and align your needs and ours. People: Leidos empowers people from every background to be themselves and gives you the tools to learn new skills by enabling growth whilst developing. We believe that extraordinary people need opportunities to grow, to be inspired and to inspire others. At Leidos, we invest in technical academies, career rotations and a career development plans that enhance your future. If you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo - because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 - and moving faster than anyone else dares. Original Posting: For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above. Pay Range: £44,700.00-£57,300.00 The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.