Gillian qualified as a Clinical Psychologist in 1986 at the Institute of Psychiatry in London. She worked at Westminster Children's Hospital and Great Ormond Street Children's Hospital before moving to St George's Hospital in South London in 1995, where she is currently Head of the Paediatric Psychology Service and an Honorary Research Fellow at St George's University, London. Her main research interest is the psychological impact on families of a child’s admission to PICU. She has recently completed a project investigating children’s memories of PICU, funded by the Health Foundation.