Principal Mechanical Engineer

Company Overview

Mott Mac Donald is a global engineering, management, and development consultancy with over 20,000 employees across more than 50 countries and 140+ offices. We work across major industries, delivering impactful projects that shape our future and support communities worldwide.

The Energy unit delivers services globally in sectors such as hydropower, nuclear, waste, renewable generation, and transmission & distribution networks. The team provides integrated engineering and project management from concept to decommissioning.

We are looking for a Principal Mechanical Engineer to join our growing Nuclear, Defence and Civil division. This role offers an exciting opportunity to work on a diverse portfolio of projects, including nuclear decommissioning, defence, and new build. You will collaborate with clients locally and nationally, contributing to the most impactful energy and infrastructure projects.

• Lead mechanical engineering aspects of multi‑discipline design projects, from feasibility to detailed design stages.
• Work on a diverse range of projects, including nuclear decommissioning, defence, and energy infrastructure.
• Liaise with clients to develop and deliver innovative solutions tailored to their needs.
• Produce and oversee high‑quality design and technical documentation.
• Provide quality assurance through surveillance, review, and checking of team outputs.
• Collaborate with multi‑disciplinary teams to deliver fit‑for‑purpose engineering solutions.
• Visit client sites as required and promote further opportunities to enhance relationships.
• Ensure safety is integral to mechanical engineering design and project delivery.
• Present and defend solutions to complex problems in client‑facing environments.

• Chartered status with the IMechE or a relevant professional body (or equivalent experience with progress toward chartered status).
• Demonstrable experience in mechanical engineering design within a highly regulated industry, preferably nuclear.
• Broad knowledge of industry standards, legislation and engineering principles.
• Strong commercial awareness, with experience in FEED (Front‑End Engineering Design) projects.
• Excellent communication skills and the ability to engage effectively with clients and stakeholders.
• Capable of managing and prioritising multiple projects in a dynamic environment.
• Client‑facing experience, with the ability to maintain and build strong relationships.
• Experience of leading, managing and working with multi‑disciplinary teams.
• Proactive in seeking input from engineers, specialists and team members to enhance outcomes.
• Committed to continuous professional development and staying abreast of industry advancements.

Please be advised that offers for this role are conditional upon obtaining the appropriate level of Security Clearance.

Mott Mac Donald Ltd. is not currently offering sponsorship to candidates under the Skilled Worker visa route in the UK. We welcome applications from candidates eligible for alternative immigration routes that do not require sponsorship.

We offer a hybrid working policy that embraces well‑being, flexibility, and trust, allowing you and your manager to choose the most effective working style.

We put equality, diversity, and inclusion at the heart of our business and commit to an inclusive environment where everyone feels they can contribute.

If you have a disability or need support during the recruitment process, please contact reaso

• Private medical insurance for all UK colleagues.
• Health cash plan to support everyday health costs.
• Access to Peppy, free support from menopause experts.
• Wellbeing support through a comprehensive programme, including family access.
• Flexibility to tailor salary to opt into a wide range of health benefits.

• We match employee pension contributions between 4.5% and 7%.
• Life assurance up to 4× your basic salary, with option to increase to 6×.
• Income protection scheme with financial benefit and support for long‑term illness.
• Flexible benefits: life…