Principal Mechanical Engineer

Job Title: Principal Mechanical Engineer

Location: Flexible, UK + Hybrid Working Arrangement

Compensation: Competitive Salary+ Benefits

Role Type: Full time / Permanent

Lead the Way in Nuclear Decommissioning

At Cavendish Nuclear we're working to create a safe and secure world, together, and if you join us, you can play your part as a Principal Mechanical Engineer, at one of our key locations: Warrington (Cheshire), Hessle (East Riding of Yorkshire), or Preston (Lancashire).

The role

As a Principal Mechanical Engineer, you'll play a pivotal role in a major civil nuclear decommissioning initiative. This project is part of a broader effort to safely dismantle and remediate legacy nuclear infrastructure, with a strong emphasis on sustainability, regulatory compliance, and environmental stewardship. You'll be working on the integration of complex mechanical systems within a multidisciplinary team, developing innovative engineering solutions to support the safe deconstruction and long-term management of nuclear facilities.

Day-to-day, you'll lead multidisciplinary engineering teams, oversee the delivery of complex technical solutions, and act as a key point of contact for customers, ensuring high standards of safety, quality, and performance while mentoring others and driving continuous improvement across projects.

• Lead and manage multidisciplinary engineering teams to deliver high-quality technical solutions aligned with customer requirements and project scope.
• Supervise and mentor engineers and technical specialists, ensuring effective performance, development, and adherence to engineering standards.
• Act as a key liaison with customers, fostering strong relationships and ensuring transparent communication on technical progress and delivery.
• Oversee the production, review, and approval of engineering outputs, including calculations, specifications, and reports, ensuring compliance with relevant codes and standards.
• Champion health, safety, and environmental standards across engineering activities, promoting a culture of best practice and continuous improvement.

This role is full time, 37 hours per week and provides hybrid working arrangements with 3 days in the office, at one of our key locations: Warrington (Cheshire), Hessle (East Riding of Yorkshire), or Preston (Lancashire).

Essential experience of the Principal Mechanical Engineer:

Although a benefit, nuclear experience is not essential and we welcome applicants from all highly regulated industries.

• Extensive experience leading multidisciplinary engineering teams and delivering complex technical projects within agreed scope, timeframes, and quality standards.
• Proven ability to supervise and mentor engineers and technical specialists, fostering professional development and ensuring high performance.
• Strong background in producing, reviewing, and approving detailed engineering outputs, including calculations, specifications, and technical reports.
• Demonstrated expertise in applying relevant procedures, codes, and standards to ensure compliance and technical integrity across engineering activities.
• Track record of effective customer engagement, including managing relationships, resolving technical issues, and supporting business development initiatives.

Qualifications for the Principal Mechanical Engineer:

• Engineering degree (or equivalent qualification) in relevant engineering discipline, with significant demonstrable experience.

Security Clearance

The successful candidate must be able to achieve and maintain Standard (BPSS) / Security Check (SC) security clearance for this role. Further details are available at United Kingdom Security Vetting: clearance levels - GOV.UK.

What we offer

• Generous holiday allowance
• Matched contribution pension scheme, with life assurance
• Access to a Digital GP, annual health check, and nutritional consultations through Aviva DigiCare+
• Employee share scheme
• Employee shopping savings portal
• Payment of Professional Fees
• Reservists in the armed forces receive 10-days special paid leave
• Holiday Trading is a benefit that allows UK Cavendish employees to buy additional leave or to sell up to one working week of annual leave from their annual entitlement. This Window opens February through to March annually.
• 'Be Kind Day' enables employees to take one working day's paid leave a year (or equivalent hours) to undertake volunteering work with their chosen organisation or registered charity
• Excellent development opportunities and benefits package including an employee assistance programme supporting physical, mental and financial wellbeing.

Cavendish

We're Cavendish Nuclear - a team of c5,000 specialists and a core part of Babcock International Group.

Here, you'll be part of something bigger. Across clean energy, defence, and civil decommissioning, your work will contribute to projects that are critical to energy security and national protection. Together, we're shaping a future that lasts - not only through the impact we make, but through meaningful careers that respect your work-life balance.

We are a disability confident committed employer. If you have a disability or need any reasonable adjustments during the application and selection stages, please email with the subject header 'Reasonable adjustments requirement'. We're committed to building an inclusive culture where everyone's free to thrive. We are happy to talk about flexible working - please ask about alternative patterns of work at interview.

Closing date: 12/02/2026