Mark William (Bill) Clark is a Chartered Civil and Structural Engineer with over four decades of experience in infrastructure, civil engineering, environmental projects and complex engineering programmes. He is the Director of SigmaSys Ltd, where he specialises in governance, assurance, forensic investigations and expert witness services related to engineering, construction and manufacturing failures. Throughout his career, Bill has held senior leadership roles including Director of Engineering at Tata Projects and Corus Infrastructure Services, CEO of Davy Markham Ltd, and Technical Director positions in major engineering consultancies. He has led large multidisciplinary engineering teams and delivered complex projects across sectors including nuclear infrastructure, rail, water utilities, energy-from-waste facilities and major urban developments. Bill regularly conducts forensic investigations into structural failures, defective design and construction, environmental incidents, and project delays or cost overruns. A Fellow of the Institution of Structural Engineers and the Institution of Civil Engineers, he also serves as a high-risk project and programme assurance assessor for the UK Government’s Infrastructure and Projects Authority, bringing deep technical and governance expertise to complex infrastructure disputes.