William J. Nuttall is Director of the MoTI Programme, Assistant Director of the ESRC Electricity Policy Research Group and University Senior Lecturer in Technology Policy at the University of Cambridge, UK. Richard Clarke is cryogenics specialist at CCFE (Culham Centre for Fusion Energy), a UK research organisation developing fusion as an alternative, long-term, sustainable and clean energy source. Bartek A. Glowacki is Reader in the Department of Materials Science and Metallurgy, University of Cambridge.