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David Wrathmall
Interim Chief Executive Officer

David Wrathmall is a graduate of University College London and a Chartered Management Accountant who has held c-level positions with broad operational remits over the last 16 years. He has worked across Europe and emerging markets, including with internationally listed companies in digital technologies, telecoms, financial services, and the research and education sectors. David has recent experience of delivering cross-border organisational restructuring programmes, including mergers and corporate restructuring, and served as Director on the main board of The Welding Institute from 2020 to 2023, whilst also chairing its Audit Committee.

David was appointed as the interim Chief Executive of TWI in April 2024.


John Hill
Director of Technology and Strategy

John spent the first decade of his forty year career in manufacturing, starting as an apprentice and becoming a Chartered Production Engineer, specialising in polymers, composites and adhesives.

In the late 1980s, he moved into manufacturing research, training and consulting, joining a similar membership-based organisation to TWI called PERA (The Production Engineering Research Association). Over a 28 year career with PERA, he rose from Consultant to Section Leader, Director of Technology, CEO and finally Chair, representing the UK RTO sector on the Board of EARTO and becoming a Fellow of the Institute of Directors.

In 2016, he moved into Whitehall to better influence the Government’s industrial strategy, and learn first-hand how the machinery of government works. There, he spent time as a Director in the Department for Business, Energy & Industrial Strategy (then BIS) and the Department for International Trade (DIT). More recently, he transferred into one of the devolved Mayoral Combined Authorities, to understand better how manufacturing innovation and skills are implemented locally. There, he performed a business turnaround of a former Local Enterprise Partnership, merged into the Combined Authority, transforming it from the poorest performing UK LEP to the highest, creating 20,000 jobs and establishing a University in Peterborough. 


Leonie Stewart
Director of Finance

Leonie joined TWI in 2019 as Business Transformation Project Manager, where she helped to implement a programme of change to prepare the business for future growth.

She has spent 26 years working in finance and operations, half of this time at Global FD and CFO level. She has worked in the USA, Middle East, Europe and Asia Pacific regions, predominantly with high growth companies in the financial markets and IT sectors. Leonie is a contributor and guest lecturer on the ‘Entrepreneurship for Physicists’ course at Imperial College, London.

Paul Woollin

Paul Woollin
Director of Research

Paul joined the Materials Department at TWI in 1992, earlier graduating and gaining a doctorate from the University of Cambridge. He specialises in the metallurgy, weldability and weld properties of stainless steels and nickel alloys. In 2000, he became Head of the Materials Department and was appointed Director of Research in 2010.


Tat-Hean Gan
Director of Membership, Innovations and Global Operations 

Tat-Hean joined TWI in 2006 after graduating with a first-class honours degree in electrical and electronics engineering from the University of Nottingham before pursuing an MSc in Advanced Mechanical Engineering, his PhD in Engineering from Warwick University and his Executive MBA degree from the University of Birmingham. Tat-Hean’s areas of expertise include non-destructive testing, signal processing and imaging techniques, structural and condition monitoring, technology transfer and exploitation, business and technology development, IP and patents, project management, collaborative programmes, public funding, international business and recruitment for engineering services. Tat-Hean was appointed the Innovation and Skills Director in 2019. He is also the Director of the Brunel Innovation Centre (BIC) and the Director of the National Structural Integrity Research Centre (NSIRC), the UK's first industry-led postgraduate education and research centre in structural integrity, which is based at TWI.


The Executive Board are supported by our Associate Directors and also comprise part of the TWI Leadership team.

Associate Directors

Leadership Team

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