Principal Mechanical Design Engineer - Mission Critical (Data Centres)Location: London (with flexibility across Europe) An established, forward-thinking engineering and architecture consultancy is expanding its mission-critical capability, with a focus on delivering large-scale, high-performance data centre projects across Europe. This is an exciting opportunity for a Principal Mechanical Design Engineer to take a leading role in shaping this offering-working closely with senior leadership to define design standards, influence strategy, and help build a high-performing team.The RoleYou will be responsible for leading the mechanical design of complex data centre projects, ensuring innovative, efficient, and resilient solutions across the full design lifecycle. This is a senior, client-facing role combining technical leadership, project oversight, and team development, with a strong emphasis on modern cooling strategies and mission-critical system performance.Key ResponsibilitiesLead mechanical design delivery for large-scale data centre developmentsAct as a key client interface, supporting early-stage design discussions and brief developmentDrive the mechanical design strategy, including cooling approaches, redundancy, and uptime performanceManage and coordinate complex design programmes (e.g. multi-discipline drawing packages)Work closely with electrical and BMS teams to ensure fully integrated MandE solutionsOversee downstream design delivery in collaboration with engineerin