Senior Networking & Security Specialist

CBSbutler Ltd.; Newbury; On-site; GBP 92,000 - 111,000; Full time

Job summary

CBSbutler Ltd. is seeking a Senior Networking & Security Specialist / Technical Lead in Newbury for a hybrid, 6-month rolling contract with an active UK SC clearance or eligibility.

The role combines hands-on implementation with technical leadership and stakeholder engagement across enterprise environments, including multi-vendor networks, HLD/LLD creation and runbook development.

Qualifications

• Extensive hands-on design and delivery experience across complex network and security solutions.
• Strong leadership in technical delivery, with stakeholder engagement and runbooks.
• Active UK SC Clearance or eligible preferred.

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.

Skills

Routing & switching

BGP

OSPF

IS-IS

EIGRP

VLAN

STP

RSTP

MSTP

vPC

LACP

QoS

VXLAN

GRE

IPsec

NGFW design

SSL/TLS

SD-WAN

Security policy

Compliance

Load balancing

SSL offloading

GSLB

High availability

Cisco IOS

IOS-XE

IOS-XR

NX-OS

ASA

Firepower

ISE

FortiOS

FortiGate

FortiManager

FortiAnalyzer

F5 BIG-IP

iRules

Education

CCIE/JNCIE or equivalent

Cisco DevNet certification

Tools

Python

Ansible

REST/NETCONF/RESTCONF/gRPC APIs

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 Center and ACI
• Juniper JunOS and SRX
• Fortinet FortiOS, FortiGate, FortiManager, 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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