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- Tasks: Lead mechanical design from concept to RIBA Stage 4 on exciting commercial projects.
- Company: A rapidly growing main contractor in the London and South East fit-out market.
- Benefits: Competitive salary, travel allowance, bonus, and generous holiday package.
- Why this job: Shape the future of mechanical design in a dynamic and impactful role.
- Qualifications: Experience in contractor-side mechanical design and strong project ownership skills.
- Other info: Opportunity to influence in-house capabilities and work on diverse projects.
The predicted salary is between 80000 - 90000 £ per year.
A growing main contractor in the London and South East commercial office fit out market is strengthening its in-house design capability and is looking for a Senior Mechanical Design Engineer to lead from the front. Trading for 3.5 years and turning over circa GBP20m in 2026, the business has built its reputation quickly and now wants the right person to help shape how its mechanical design function develops.
This is a contractor-side role with genuine ownership from feasibility and concept through to RIBA Stage 4 technical design. The focus is firmly on delivery: programme, procurement, installability, change control and margin.
You will lead mechanical design across multiple projects, coordinate external consultants and design partners, and challenge outputs where needed, including reviewing IES, Revit and Hevacomp information. You will produce feasibility schemes and option studies to support pre-con decisions, and when budgets tighten you will lead value engineering conversations with confidence, presenting practical alternatives that protect performance and quality.
You will also support tender and proposal submissions, attend design and client meetings, and produce clear actions, trackers and reporting, working closely with the commercial team on subcontractor tender analysis.
They need someone with contractor-side mechanical design experience (D&B, design assist, or delivery-led design), who can evidence project ownership and interface management, and who is confident carrying designs through to Stage 4. You should be comfortable across Cat A, Cat B, turnkey and D&B environments, present well with clients, and able to explain design decisions in commercial terms, not just technical language.
Strong Excel and PowerPoint skills are important, alongside a minimum HNC/HND in Building Services Engineering (or equivalent) and typically five or more years relevant experience with D&B exposure.
- Contractor-side mechanical design lead, concept to RIBA Stage 4
- Delivery-led decision making: programme, procurement, installability, change control, margin
- Commercial fit out focus across London and the South East
- Mechanical packages typically GBP250k - GBP1.5m, overall project values up to circa GBP4m
- GBP80,000 - GBP90,000 + package, travel covered/allowance, bonus, 25 days holiday + bank holidays + birthday
This won’t suit a consultancy-only profile with no contractor-side delivery exposure, or anyone unable to demonstrate ownership beyond producing design outputs. If you want a role where design is judged by what gets built, and you have the scope to shape an in-house mechanical capability within a growing contractor, this is worth a conversation.
Lead / Principal Mechanical Design Engineer employer: James Lewis Recruitment
Contact Detail:
James Lewis Recruitment Recruiting Team
StudySmarter Expert Advice 🤫
We think this is how you could land Lead / Principal Mechanical Design Engineer
✨Tip Number 1
Network like a pro! Get out there and connect with industry professionals, attend events, and join relevant groups. The more people you know, the better your chances of hearing about opportunities that might not even be advertised.
✨Tip Number 2
Show off your skills! Create a portfolio that highlights your best work in mechanical design. Include case studies that demonstrate your project ownership and decision-making abilities. This will give potential employers a clear picture of what you can bring to the table.
✨Tip Number 3
Prepare for interviews by practising common questions and scenarios related to contractor-side roles. Be ready to discuss how you've handled challenges in past projects, especially around delivery-led decision making and value engineering.
✨Tip Number 4
Don’t forget to apply through our website! We’re always on the lookout for talented individuals like you. Plus, it’s a great way to ensure your application gets seen by the right people in our team.
We think you need these skills to ace Lead / Principal Mechanical Design Engineer
Some tips for your application 🫡
Show Your Experience: Make sure to highlight your contractor-side mechanical design experience. We want to see how you've taken projects from concept to RIBA Stage 4 and how you've managed interfaces and ownership throughout the process.
Be Clear and Concise: When writing your application, keep it straightforward. Use clear language to explain your design decisions in commercial terms, not just technical jargon. We appreciate a well-structured application that gets straight to the point!
Tailor Your Application: Don’t just send a generic CV and cover letter. Tailor your application to reflect the specific requirements of the role. Mention your experience with value engineering and how you’ve successfully navigated tight budgets in past projects.
Apply Through Our Website: We encourage you to apply directly through our website. It’s the best way for us to receive your application and ensures you’re considered for this exciting opportunity to shape our mechanical design function!
How to prepare for a job interview at James Lewis Recruitment
✨Know Your Stuff
Make sure you brush up on your mechanical design principles, especially those related to contractor-side work. Be ready to discuss your experience with RIBA Stage 4 and how you've led projects from concept to completion.
✨Showcase Your Leadership Skills
Prepare examples of how you've taken ownership of projects and managed teams or external consultants. Highlight your ability to challenge outputs and lead value engineering discussions confidently.
✨Speak Their Language
When discussing your designs, focus on commercial terms as well as technical details. Be prepared to explain how your decisions impact the project's budget and overall success, showing that you understand the bigger picture.
✨Get Familiar with Tools
Since strong Excel and PowerPoint skills are essential, practice using these tools to present your ideas clearly. Consider preparing a mock presentation that showcases your design process and decision-making for a project.