Stephen Walker is Reader at The University of Sheffield. He is author of Gordon Matta-Clark: Art, Architecture and the Attack on Modernism (I.B.Tauris, 2009) and is co-editor, with Florian Kossak, Doina Petrescu, Tatjana Schneider and Renata Tyszczuk, of Agency: Working With Uncertain Architectures (2009). Less