Having graduated in Agronomy at Brussels Free University, William began his career working on the restructuring of agriculture (Hainaut, Belgium).In 1989 he joined the NGO “Fonds de cooperation au Développement”, becoming Projects Director.William was the Managing Director of AEIDL between 1995 and 2007. He is currently member of the board.As the Managing Director of AEIDL, William carried out many evaluations, provided advice and training, notably for the LEADER European Observatory, which he managed in 2000-2001.In 2009, he joined the Directorate-General for Agriculture, Natural Resources and the Environment of the Walloon Region, in preparation of the Belgian Presidency of the EU.He was a negotiator for the EU to the Conference of the Parties to the Convention on Biological Diversity in Nagoya (COP10), to the Subsidiary Body on Scientific, Technical and Technological Advice (SBSTTA14), the Working Group on the Review of the Implementation of the Convention (WGRI3), and the Standing Committee of the Bern Convention. He was responsible for monitoring the implementation of the "decisions of Nagoya", and especially the Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilization.William is President of COTA, an independent association for international solidarity, which aims to build capacity of stakeholders – North and south – who influence or participate in the development process.He was also a member of the Board of Directors of the Free University of Brussels (1983-1984).