We seek experienced Senior & Principal Mechanical Engineers to join my client's offices in London or Paris. The ideal candidates will have at least 7 years of experience, demonstrating leadership in managing medium to large projects and maintaining client relationships. You will oversee the development, design, and coordination of engineering projects, with a focus on mechanical and electrical installations across various building types. Key Responsibilities: Lead large-scale projects, ensuring the design, development, and coordination of engineering services, particularly for mechanical and electrical systems. Act as the primary client contact, representing the company at technical meetings with clients, contractors, and professional teams. Develop and specify controls, instruments, and systems for building services, ensuring compliance with functional specifications and client requirements. Survey and test existing installations, prepare dilapidation reports and ensure designs meet legal and industry standards. Coordinate engineering services holistically, focusing on the integration of engineering solutions across projects. Validate input from junior engineers and oversee project delivery, ensuring compliance with project management, financial, and quality assurance protocols. Role Requirements: BSc/BEng in a relevant engineering discipline or equivalent experience. Progressing toward or already holding Chartered Engineer status (MCIBSE/MIEE). Extensive experience in specification design across multiple building types, particularly in sectors such as data centres, healthcare, pharmaceutical, commercial, labs, or clean rooms. Right to work in the UK without sponsorship Strong knowledge of UK/EU Health & Safety regulations, BS standards, and industry codes. Proficiency in MS Office, engineering design software, and IT-based calculation tools. Ability to prioritise workloads, meet deadlines, and manage teams effectively. Experience with international consultancy operations is preferred, as is a background in consulting or construction. You must adhere to ethical guidelines and practices, ensuring projects are delivered to the highest professional standards. This role offers a unique opportunity to lead significant projects that will have a lasting impact. We provide a collaborative and innovative work environment where you can grow professionally and contribute to cutting-edge projects contributing to the company's continued growth and success. Join my client and be part of a team that is shaping the future of data centre infrastructure.