Senior Network Engineer

  • Thorn SDS
  • Corsham, Wiltshire
  • 06/08/2026
Full time Information Technology Telecommunications Cisco

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Cisco Routing & Switching Firewalls VPN VMware NSX LAN/WAN ITIL Defence

Help secure the networks that support the UK's critical defence operations.

Are you an experienced Network Engineer looking for a role where your expertise has a genuine operational impact?

We're looking for a Senior Network Engineer to join a nationally significant UK Defence programme, supporting the secure, resilient network infrastructure that enables mission critical operations across the UK and overseas.

Working in one of the UK's most secure IT environments, you'll design, maintain and optimise enterprise network infrastructure while helping deliver the next generation of deployable IT services for the Ministry of Defence.

If you thrive on solving complex networking challenges and want to work with cutting edge technologies in an environment where reliability and security are paramount, we'd love to hear from you.

About Thorn SDS

Thorn SDS is a specialist Managed Service Provider headquartered in Alton, Hampshire. We partner with organisations across the Space, Defence and Security sectors, connecting exceptional technical professionals with some of the UK's most challenging and rewarding engineering programmes.

About the Programme

You'll be joining a major transformation programme modernising the Ministry of Defence's deployable IT capability.

Replacing legacy communication and information systems with modern, secure and resilient platforms, the programme is delivering next-generation technology.

As part of the Through Life Support (TLS) team, you'll help ensure these critical services remain secure, available and fully operational throughout their lifecycle.

The Role

As a Senior Network Engineer, you'll provide advanced 2nd and 3rd line support across enterprise network infrastructure, ensuring the availability, performance and security of critical operational services.

Working alongside Service Operations, Resolver Groups and specialist engineering teams, you'll troubleshoot complex network issues, implement infrastructure improvements and support secure deployments across both fixed and deployable environments.

This is an excellent opportunity for an experienced engineer who enjoys working with enterprise networking technologies in highly secure, mission critical environments.

What You'll Be Doing
  • Supporting and maintaining enterprise LAN, WAN and operational network infrastructure.
  • Configuring, managing and troubleshooting routers, switches, firewalls and VPN technologies.
  • Investigating and resolving complex Layer 2, Layer 3 and Layer 4 networking issues.
  • Supporting Software Defined Networking technologies, including VMware NSX.
  • Monitoring network performance, capacity and availability to ensure optimum service delivery.
  • Implementing network upgrades, changes and security improvements.
  • Supporting ITIL-aligned incident, problem and change management processes.
  • Working closely with infrastructure, applications and security teams to resolve technical issues.
  • Supporting deployments across both on premises and operational environments.
  • Maintaining network resilience while ensuring compliance with MOD security policies and standards.
What We're Looking For

You'll also have excellent analytical, troubleshooting and communication skills and be comfortable working full time onsite in Corsham.

We're particularly interested in candidates with experience in:

  • Enterprise routing and switching (Layer 2 & Layer 3).
  • Cisco networking technologies.
  • Firewalls, VPNs and secure remote connectivity.
  • VMware NSX or other Software Defined Networking technologies.
  • Network monitoring, performance optimisation and troubleshooting.
  • Layer 4 application dependencies and network performance analysis.
  • Enterprise infrastructure within secure or highly regulated environments.
  • Defence, MOD or other security sensitive environments (desirable).
What's In It For You?

Alongside a competitive salary of £65,000-£75,000, you'll receive:

  • 25 days' annual leave plus Bank Holidays.
  • Employer pension contributions.
  • Group Life Insurance.
  • Wellbeing services including GP access, physiotherapy and lifestyle savings.
  • Employee Referral Scheme.
  • Funded training, certifications and ongoing professional development.
  • The opportunity to work on one of the UK's most significant defence technology programmes.
  • Exposure to enterprise scale networking technologies within a highly secure environment.
  • The chance to collaborate with experienced engineers on complex infrastructure projects that directly support UK defence capability.
Security Requirements

Applicants must have the right to work in the UK and either already hold, or be eligible to obtain, a high level of UK National Security Clearance.

Please note that, due to the nature of our work, nationality, previous nationalities and country of birth may affect eligibility for certain security cleared positions.