We are looking for a Senior Control Systems Engineer to be based full time onsite in Warrington or Cumbria. This is a contract role Inside IR35 at the market rates. Candidates can start with BPSS security clearance whilst higher level clearance is being undertaken. You should be British Citizens and passport holders and not have worked outside the UK during the past 5 years. SUMMARY: Working as part of an integrated, multi-disciplinary team, you will take technical responsibility for the design, implementation, testing, and commissioning of PLC, HMI / SCADA-based control systems across the full project lifecycle. This is a hands-on senior engineering role, ideal for an engineer who enjoys technical ownership, problem-solving, and mentoring others, while supporting Lead Engineers and Project Managers in delivering high-quality solutions in regulated environments. KEY RESPONSIBILITIES: Deliver detailed design, implementation, testing, and commissioning of control systems in line with project requirements. Take ownership of assigned control system deliverables, ensuring they are produced to a high technical and quality standard. Configure and develop PLC software, control philosophies, and system configurations using industry-standard platforms. Develop and deploy simulator applications to support the testing and verification of PLC software. Support integration of control systems with electrical, mechanical, and wider engineering disciplines. DESIGN & DOCUMENTATION: Produce comprehensive and high-quality control system documentation including: Operation & Maintenance Manuals Control System Training Material Review and check design documentation and software produced by other engineers. Interpret and work from engineering design drawings including PLC/SCADA control enclosures, I/O interfacing and marshalling cubicles and operator control panels. Support site visits to identify constraints, risks and design impacts. TESTING, VALIDATING & COMMISSIONING: Plan and execute formal verification and validation testing including internal testing (FAT), customer witness testing (CAT) and site acceptance / commissioning activities. Undertake fault-finding and troubleshooting during in-house testing and site activities, resolving complex technical issues efficiently. Ensure systems are delivered in line with safety, quality, and performance requirements. PROJECT & TEAM SUPPORT: Work closely with the Lead Engineer and Project Manager to support delivery against programme and milestones. Provide accurate effort estimates for scope changes or additional works, including input to project schedules (plans). Contribute to and support design reviews and technical workshops. Interface effectively with the integrated design team, facility teams, systems engineering, and other project functions. COMPLIANCE & SAFETY: Produce reports and documentation required to comply with CDM regulations. Ensure control system designs align with applicable standards, client requirements, and regulatory expectations. ESSENTIAL: HND or Degree in Engineering (Electrical, Control Systems, Automation) or equivalent experience. Proven experience in the design and implementation of PLC-based control systems. Strong knowledge of IEC 61131 PLC programming languages, PLC hardware, software, and industrial communication protocols. Experience delivering projects through detailed design, implementation, testing, and commissioning. Demonstrated experience of formal testing, validation and verification activities, with use of simulator tools/applications where applicable. Strong fault-finding and troubleshooting skills across complex control systems. Good understanding of electrical and control system design drawings. Ability to work independently and as part of an integrated delivery team, often to challenging timescales. Excellent written and verbal communication skills with strong technical documentation capability. Strong interpersonal skills with the ability to collaborate effectively at all levels. DESIRABLE: Experience working in regulated or safety-critical industries such as Nuclear, MOD, or Pharmaceuticals. Experience with Rockwell and/or Schneider PLC and HMI/SCADA platforms. Knowledge of OT cyber security principles and secure-by-design control systems. Experience of functional safety systems. Awareness of Sellafield Engineering Standards. Professional registration (CEng, IEng) or equivalent. Certified training on Rockwell and/or Schneider PLC systems.