Senior Networking & Security Specialist

CBSbutler Holdings Limited trading as CBSbutler; Shaw; Hybrid; GBP 92,000 - 111,000; Full time

Job summary

CBSbutler Holdings Limited trading as CBSbutler is seeking a Senior Networking & Security Specialist / Technical Lead for a 6-month rolling contract in Newbury (hybrid). The role demands hands-on leadership, design, and delivery of complex enterprise network and security solutions across greenfield and brownfield environments.

You will produce and validate high‑level and low‑level designs, engage stakeholders, and guide engineers through the project lifecycle while maintaining security and

Qualifications

• Experience across complex network and security solutions.
• Ability to design high level and low level designs (HLD/LLD).
• Hands-on implementation and stakeholder engagement required.

Responsibilities

• Lead design and implementation of complex network and security solutions across environments.
• Produce high-quality HLDs, LLDs, implementation plans and runbooks.
• Perform design validation, PoC testing and verification.
• Configure, deploy and optimize network and security infrastructure.
• Diagnose and resolve complex incidents.
• Conduct capacity planning and technical assessments.
• Act as primary technical point of contact for stakeholders.
• Present designs and strategies to diverse audiences.
• Coordinate engineers with project lifecycle teams.

Skills

Routing & Switching

BGP OSPF IS-IS EIGRP

VLAN STP RSTP MSTP

VXLAN GRE IPsec

Cisco ACI

Network Security

NG Firewall

SSL/TLS SD-WAN

Tools

Cisco IOS/IOS-XE/IOS-XR/NX-OS

ASA Firepower ISE

Catalyst/Aci

Juniper JunOS SRX

Fortinet FortiOS FortiGate

F5 BIG-IP

Job description

Senior Networking & Security Specialist / Technical Lead

Location: Newbury - Hybrid, 1-2 days per week onsite

Contract: 6 months rolling

Security Clearance: Active or eligible for UK SC Clearance

Rate: £500-£600 per day, inside IR35

We are looking for an experienced Senior Networking & Security Specialist / Technical Lead to join a high-level technical delivery team, leading the design and hands-on implementation of complex, multi-vendor network and security solutions across enterprise environments.

This is a hands-on role combining technical leadership, solution design, implementation and stakeholder engagement.

Key Responsibilities

• Lead the design and implementation of complex network and security solutions across greenfield and brownfield environments
• Produce high-quality HLDs, LLDs, implementation plans and operational runbooks
• Perform design validation, PoC testing and pre/post-implementation verification
• Configure, deploy and optimise network and security infrastructure
• Diagnose and resolve complex network and security incidents
• Conduct technical assessments and capacity planning
• Act as the primary technical point of contact for project stakeholders
• Present technical designs and implementation strategies to technical and non-technical audiences
• Coordinate engineers and technicians, providing technical leadership and mentoring
• Work closely with project managers, solution architects, client teams and operations throughout the project lifecycle

Technical Experience Required

We're particularly interested in candidates with strong experience across:

Networking

• Advanced routing & switching
• BGP, OSPF, IS-IS and EIGRP
• VLAN, STP/RSTP/MSTP, vPC/LACP and QoS
• VXLAN, GRE and IPsec
• Enterprise and service-provider environments

Cisco ACI, including spine-leaf architecture and multi-pod/multi-site

• Network Security

Next-Generation Firewall design and implementation

• IPsec, SSL/TLS and SD-WAN security
• Security policy and lifecycle management
• Compliance-aligned network security

Application Delivery

• L4/L7 load balancing
• SSL offloading
• Global Server Load Balancing (GSLB)
• High-availability architectures

Vendor Technologies

• Cisco IOS/IOS-XE/IOS-XR/NX-OS, ASA, Firepower, ISE, Catalyst Centre and ACI
• Juniper JunOS and SRX
• Fortinet FortiOS, FortiGate, FortiManager and FortiAnalyzer
• F5 BIG-IP LTM/GTM/ASM/APM and iRules

Desirable

• Network automation experience using Python and/or Ansible
• Experience integrating network platforms via REST/NETCONF/RESTCONF/gRPC APIs
• Professional-level networking certifications such as CCIE, JNCIE or equivalent
• Cisco DevNet certification

What We're Looking For

You’ll need to be a confident technical lead who can take ownership of complex deliverables, communicate technical concepts clearly, solve problems under pressure and work effectively with both technical and business stakeholders.

If you're an experienced Network & Security Specialist looking for your next contract opportunity in a technically challenging environment, we'd love to hear from you.

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