Marc is Director of the Sydney Policy Lab. Previously, Marc was professor of political theory at the University of Oxford and chief executive of the New Economics Foundation, one of the United Kingdom's largest think tanks. His work focused on deepening partnerships with community groups who are often overlooked in the policy process. Between 2012 and 2015 he was chief speechwriter to the UK Labour Party, a co-author of the party’s 2015 election manifesto and a member of the party's general election steering committee.

He has also advised a number of commercial and non-commercial organisations on strategic communication, democratic inclusion and community engagement. In his academic work, Marc is an expert in democratic theory and the history of ideologies and social movements. He is the author of Demanding Democracy (2010), Progressives, Pluralists and the Problems of the State (2002) and an editor of many volumes, including The Oxford Handbook of Political Ideologies (2014).