Christopher Woodhouse, MB, FRCS, FEBU, is an Emeritus Professor of Adolescent Urology at University College London and previously a consultant at the Royal Marsden Hospital. He trained under Sir David Innes Williams at the Institute of Urology and was made Professor of Adolescent Urology at UCL in 2006. He is widely considered as one of the world's leading experts in reconstructive urology and in particular, adolescent urology and congenital urological anomalies. Alex Kirkham, MB BCh, FRCS, FRCR, MD, is a consultant uro-radiologist at University College London Hospitals, London, UK.