Sebastian was formerly a partner at a leading global public affairs consultancy. Prior to this, he was head of the competition practice at a strategic communications agency. He worked as an attorney at a magic circle firm, specialising in Antitrust, Competition and Trade law, as well as being a member of the Public Policy practice. He has also worked at the European Commission, and was part of its Delegation to the United States in 2000.

Sebastian has written articles on legal and political developments in various publications, including Europe’s World, Bloomberg Business Law Review and European Competition Law Review. He has also been a commentator on broadcast media including CNBC and Bloomberg TV.