Joe Brierley1, Stephen Playfor2, Samiran Ray3. 1. Paediatric Bioethics Centre, NIHR Great Ormond Street Hospital Biomedical Research Centre, London WC1N 3JH, UK. Electronic address: joe.brierley@gosh.uk. 2. Paediatric Intensive Care Unit, Royal Manchester Children's Hospital, Manchester, UK. 3. Paediatric Bioethics Centre, NIHR Great Ormond Street Hospital Biomedical Research Centre, London WC1N 3JH, UK.