Mark Birkin is Professor of Spatial Analysis and Policy and Director of the Consumer Data Research Centre (CDRC) at the University of Leeds. His major interests are in simulating social and demographic change within cities and regions, and in understanding the impact of these changes on the need for services like housing, roads and hospitals, using techniques of microsimulation, agent-based modelling and GIS. He has also been involved with many retail-based projects with a number of major blue-chip clients. Graham Clarke is Professor of Business Geography at the University of Leeds. He has worked extensively in various areas of GIS and applied spatial modelling, focusing on many applications within urban/ social geography. Graham specialises in retail geography and model development in relation to retail store location planning. His major research interests relate to retail location planning in relation to the multi- channel growth strategies of retail organisations. Martin Clarke is Professor of Geographic Modelling in the School of Geography, University of Leeds, and Deputy Director of the Consumer Data Research Centre. Martin’s main interests are based around service analysis and planning. From 1990 to 2004 he was Chief Executive of GMAP Ltd, one of the most successful university spin- out companies in the UK that specialised in network planning and location analysis for some of the world’s largest retail corporations.